Almost each desktop PC has one. They have billions of transistors, can use lots of of watts of energy, and may value over a thousand {dollars}. They are masterpieces of digital engineering and generate extremes in product loyalty and disdain… and but the variety of issues they usually do might be counted one only one hand. Welcome to the world of graphics playing cards!

Graphics playing cards are among the many PC elements to which we dedicate probably the most time on TechSpot, so clearly they want a correct dissection. Let’s assemble the workforce and head for the working desk. It’s time to delve into the innards that make up a graphics card, splitting up its numerous components and seeing what every bit does.

TechSpot’s Anatomy of Computer Hardware Series

You might need a desktop PC at work, faculty, or residence. You may use one to work out tax returns or play the newest video games; you may even be into constructing and tweaking computer systems. But how properly have you learnt the elements that make up a PC?

Enter the dragon

Ah, the common-or-garden graphics card, or to provide it a extra fulsome title: the video acceleration add-in enlargement card. Designed and manufactured by world, multi-billion greenback companies, they’re usually the biggest and singularly costliest part inside a desktop PC.

Right now on Amazon, the highest 10 greatest promoting ones vary from simply $53 to an eye-watering $1,200, with the latter coming in it 3.Three kilos (1.5 kg) in weight and over 12 inches (31 cm) in size. And all of that is to do what, precisely? Use silicon chips on a circuit board to, for many customers, create 2D & 3D graphics, and encode/decode video indicators.

That feels like a whole lot of metallic, plastic, and cash to do just some issues, so we higher get caught into one and see why they’re like this. For this anatomy piece, we’re utilizing a graphics card made by XFX, a Radeon HD 6870 just like the one we examined approach again in October 2010.

First glances do not reveal a lot: it is fairly lengthy at practically 7 inches (22 cm) however most of it appears to be plastic. We can see a metallic bracket, to carry it firmly in place within the pc, a giant purple fan, and a circuit board connector.

Let’s flip it over and see if there’s extra to be seen on the opposite facet:

The very first thing you discover is one other metallic bracket, framing a complete host of digital elements. The remainder of the circuit board in all fairness empty, however we will see plenty of connecting wires coming from the center part, so there’s clearly one thing vital there and it have to be fairly complicated…

It’s sizzling as heck in right here!

All chips are built-in circuits (ICs, for brief) and so they generate warmth after they’re working. Graphics playing cards have 1000’s of them packed right into a small quantity, which implies they’re going to get fairly toasty if the warmth is not managed indirectly.

As a outcome, most graphics playing cards are hidden beneath some type of cooling system and ours isn’t any exception. Out with the screwdrivers and in with a blatant disregard for guarantee warning stickers… it is a fairly outdated unit anyhow:

This cooling system is commonly known as a ‘blower’ sort: it sucks air from inside the pc case, and drives it throughout a big chunk of metallic, earlier than blasting it out of the case.

In the picture above, we will see the metallic block, and sticking to it are the stays of a runny substance commonly known as thermal paste. Its job is to fill within the microscopic gaps between the graphics processor (a.ok.a. the GPU) and the metallic block, in order that warmth will get transferred extra effectively.

We may also see Three blue strips referred to as thermal pads, because the delicate, squishy materials offers a greater contact between some components on the circuit board and the bottom of the cooler (which can be metallic). Without these strips, these components would barely, if in any respect, contact the metallic plate and would not be cooled.

Let’s take a better take a look at the principle chunk of metallic — in our instance, it is a block of copper, with Three copper pipes coming off it, into a number of rows of aluminum fins. The identify for complete factor is a heatsink.

The pipes are hole and sealed at each ends; inside there’s a small amount of water (in some fashions, it is ammonia) that absorbs warmth from the copper block. Eventually, the water heats up a lot that it turns into vapor and it travels away from the supply of the warmth, to the opposite finish of the pipe.

There, it transfers the warmth to the aluminum fins, cooling again down within the course of and develop into a liquid once more. The interior floor of the pipes is tough, and a capillary motion (additionally referred to as wicking) carries the water throughout this floor till it reaches the copper plate once more.

Heatpipes, as they’re generally referred to as, do not seem on each graphics card. A price range, low-end mannequin will not produce a lot warmth and so will not want them. The similar fashions usually do not use copper for the heatsink, to economize, as proven within the picture beneath.

This Asus GeForce GT 710 reveals the everyday strategy for the low-end, low-power graphics playing cards market. Such merchandise not often use greater than 20W {of electrical} energy, and despite the fact that most of that finally ends up as warmth, it is simply not sufficient to hassle the chip hiding below the cooler.

One drawback with the blower sort of cooler is that the fan used to blast air throughout the metallic fins (after which out of the PC case), has bought a troublesome job to do and so they’re often no wider than the graphics card itself. This means they should spin fairly quick, and that generates plenty of noise.

The frequent answer to that drawback is the open cooler — right here the fan simply directs air down into the fins, and the remainder of the plastic/metallic surrounding the fan simply lets this sizzling air into the PC case. The benefit of that is that the followers might be larger and spin slower, typically leading to a quieter graphics card. The draw back? The card is bulkier and the within temperature of the pc might be greater.

Of course, you do not have to make use of air to go all Netflix and chill together with your graphics card. Water is basically good at absorbing warmth, earlier than it rises in temperature (roughly Four occasions higher than air), so naturally you should buy water cooling kits and set up them, or promote a kidney or two, and purchase a graphics card with one already fitted.

The card above is EVGA’s GeForce RTX 2080 Ti KiNGPiN GAMING – the blower cooler is only for the RAM and different elements on the circuit board; the principle processing chip is water cooled. All yours for a snip at $1,800.

You could also be stunned to know that the RTX 2080 Ti has a ‘regular’ most energy consumption of 250W, which is much less that the RX 5700 XT we talked about just a little earlier.

Such extreme cooling programs aren’t there for on a regular basis, run-of-the-mill settings although: you’d go along with one in every of these setups, if you wish to elevate the voltages and clock speeds to ludicrous ranges, and spit fireplace like an actual dragon.

The brains behind the brawn: Enter the GPU

Now that we have stripped off the cooling system from our graphics card, let’s examine what we have now: a circuit board with a chunky chip within the center, surrounded by smaller black chips, and a plethora {of electrical} elements all over the place else.

No matter what graphics card you’ve, all of them have the identical type of components and observe an identical structure. Even if we go all the way in which again to 1998, and look an historic ATi Technologies graphics card, you possibly can nonetheless see roughly the identical factor:

Like our disassembled HD 6870, there’s a big chip within the center, some reminiscence, and a bunch of elements to maintain all of it operating.

The large processor goes by many names: video adapter, 2D/3D accelerator, graphics chip to call just some. But lately, we are likely to name it a graphics processing unit or GPU, for brief. Those Three letters have been in use for many years, however Nvidia will declare that they had been first to make use of it.

Not that it issues right now. All GPUs have just about the identical construction contained in the chip we see:

This processor was designed by AMD and manufactured by TSMC; it has codenames similar to TeraScale 2 for the general structure, and Barts XT for the chip variant. Packed into 0.Four sq. inches (255 mm2) of silicon are 1.7 billion transistors.

This mind-boggling variety of digital switches make up the completely different ASICs (utility particular built-in circuits) that GPUs sport. Some simply do set math operations, like multiplying and including two numbers; others learn values in reminiscence and convert them right into a digital sign for a monitor.

GPUs designed to plenty of issues all on the similar time, so a big share of the chip’s construction consists of repeated blocks of logic items. You can see them clearly within the following (closely processed) picture of AMD’s present Navi vary of GPUs:

See how there are 20 copies of the identical sample? These are the principle calculating items within the chip and do the majority of the work to make 3D graphics in video games. The strip that runs roughly down the center is generally cache — excessive velocity inner reminiscence for storing directions and knowledge.

On the sides, prime and backside, are the ASICs that deal with communications with the RAM chips on the cardboard, and the far proper of the processor homes circuits for speaking to the remainder of the pc and encoding/decoding video indicators.

You can learn up in regards to the newest GPU designs from AMD and Nvidia, in addition to Intel, if you need a greater understanding of the center of the GPU. For now, we’ll simply level that if you wish to play the newest video games or blast by way of machine studying code, you are going to want a graphics processor.

But not all GPUs come on a circuit board that you simply jam into your desktop PC. Lots of CPUs have just a little graphics processor constructed into them; beneath is an Intel press shot (therefore the somewhat blurry nature to it) of a Core i7-9900Ok.

The coloring has been added to determine numerous areas, the place the blue part on the left is the built-in GPU. As you possibly can see it takes up roughly one third of your complete chip, however as a result of Intel by no means publicly states transistor counts for his or her chips, it is exhausting to inform simply how ‘large’ this GPU is.

We can estimate, although, and examine the biggest and smallest GPUs that AMD, Intel, and Nvidia provide out of the newest architectures:

Manufacturer AMD Intel Nvidia
Architecture RNDA Gen 9.5 Turing
Chip/mannequin Navi 10 Navi 14 GT3e GT1 TU102 TU117
Transistors depend (billions) 10.3 6.4 Some Fewer 18.6 4.7
Die dimension (mm2) 251 158 Around 80? 30 or so 754 200

The Navi GPUs are constructed on a TMSC 7nm course of node, in comparison with Intel’s personal 14nm and a specifically refined 16nm node that TMSC provides for Nvidia (it is referred to as 12FFN); this implies you possibly can’t straight examine between them, however one factor is for positive — GPUs have tons of transistors in them!

To give a way of perspective, that 21 yr outdated Rage IIC processor proven earlier has 5 million transistors packed right into a die dimension of 39 mm2. AMD’s smallest Navi chip has 1,280 occasions extra transistors in an space that is solely Four occasions bigger — that is what 2 a long time of progress appears like.

An elephant by no means forgets

Like all desktop PC graphics playing cards, ours has a bunch of reminiscence chips soldered onto the circuit board. This is used to retailer all the graphics knowledge wanted to create the photographs we see in video games, and is almost at all times a kind of DRAM designed particularly for graphics functions.

Initially referred to as DDR SGRAM (double knowledge fee synchronous graphics random entry reminiscence) when it appeared available on the market, right now now goes by the abbreviated identify of GDDR.

Our explicit pattern has 8 Hynix H5GQ1H23AFR GDDR5 SDRAM modules, operating at 1.05 GHz. This sort of reminiscence remains to be discovered on plenty of playing cards accessible right now, though the trade is mostly shifting in the direction of the newer model, GDDR6.

GDDR5 and 6 work in an identical approach: a baseline clock (the one talked about above) is used to time the problem of directions and knowledge transfers. A separate system is then used to shift bits to and from the reminiscence modules, and that is accomplished as a block switch internally. In the case of GDDR5, Eight x 32 bits is processed for every learn/write entry, whereas GDDR6 is double that worth.

This block is ready as a sequential stream, 32 bits at a time, at a fee that is managed by a unique clock system once more. In GDDR5, this runs at twice the velocity of the baseline clock, and knowledge will get shifted twice per tick of this explicit clock.

So in our Radeon HD 6870, with 8 Hynix chips in complete, the GPU can switch as much as 2 (switch per tick) x 2 (double knowledge clock) x 1.05 (baseline clock) x 8 (chips) x 32 (width of stream) = 1075.2 Gbits per second or 134.Four GB/s. This calculated determine is called the theoretical reminiscence bandwidth of the graphics card, and customarily, you need this to be as excessive as attainable. GDDR6 has two switch fee fashions, regular double fee and a quad mannequin (double the double!).

Not all graphics playing cards use GDDR5/6. Low-end fashions usually depend on older DDR3 SDRAM (such because the passively cooled instance we confirmed earlier), which is not designed particularly for graphics functions. Given that the GPU on these playing cards might be fairly weak, there is not any loss in utilizing generic reminiscence.

Nvidia dabbled with GDDR5X for some time — it has the identical quad knowledge fee as GDDR6, however cannot be clocked as quick — and AMD has used HBM (High Bandwidth Memory) on-and-off for a few years, within the likes of the Radeon R9 Fury X, the Radeon VII, and others. All variations of HBM provide enormous quantities of bandwidth, nevertheless it’s costlier to fabricate in comparison with GDDR modules.

Memory chips must be straight wired to the GPU itself, to make sure the very best efficiency, and generally meaning the traces ({the electrical} wiring on the circuit board) could be a little bizarre trying.

Notice how some traces are straight, whereas others observe a wobbly path? This is to make sure that each electrical sign, between the GPU and the reminiscence module, travels alongside a path of precisely the identical size; this helps prevents something untoward from occurring.

The quantity of reminiscence on a graphics card has modified quite a bit because the first days of GPUs.

The ATi Rage 3D Charger we confirmed earlier sported simply 4MB of EDO DRAM. Today, it is a thousand occasions higher, with Four to six GB being the anticipated norm (prime finish fashions usually double that once more). Given that laptops and desktop PCs are only recently shifting away from having Eight GB of RAM as customary, graphics playing cards are veritable elephants relating to their reminiscence quantities!

Ultra quick GDDR reminiscence is used as a result of GPUs must learn and write plenty of knowledge, in parallel, on a regular basis they’re working; built-in GPUs usually do not include what’s referred to as native reminiscence, and as an alternative, must depend on the system’s RAM. Access to that is a lot slower than having gigabytes of GDDR5 proper subsequent to the graphics processor, however these sorts of GPUs aren’t highly effective sufficient to essentially require it.

I demand energy and many it

Like any system in a pc, graphics playing cards want electrical energy to work. The quantity they want largely will depend on what GPU the cardboard is sporting because the reminiscence modules solely want a few watts every.

The first approach that the cardboard can get its energy is from the enlargement slot it is plugged into, and nearly each desktop PC right now makes use of a PCI Express connection.

In the picture above, the ability is provided by the smaller strip of pins to the left – the lengthy strip on the precise is only for directions and knowledge switch. There are 22 pins, 11 per facet, within the brief strip however not all of these pins are there to energy the cardboard.

Almost half the 22 pins are for basic system duties — checking the cardboard is okay, easy powering on/off directions, and so forth. The newest PCI Express specification locations limits as to how a lot present might be drawn, in complete, off the 2 units of voltage strains. For trendy graphics playing cards, it is Three amps off the +3.3V strains and 5.5 amps off the +12; this offers a complete of (Three x 3.3) + (5.5 x 12) = 75.9 watts of energy.

So what occurs in case your card wants greater than that? For instance, our Radeon HD 6870 pattern wants at the least 150W — double what we will get from the connector. In these instances, the specification offers a format that may be adopted by producers within the type of further +12V strains. The format is available in two sorts: a 6 pin and an Eight pin connector.

Both codecs present three extra +12 voltage strains; the distinction between them lies within the variety of floor strains: three for the 6 pin and 5 for the Eight pin model. The latter permits for extra present to be drawn by way of the connector, which is why the 6 pin solely offers a further 75W of energy, whereas the bigger format pushes this as much as 150W.

Our card has two 6 pin connectors, so with the PCI Express enlargement slot, it will probably take up 75 + (2 x 75) = 225 watts of energy; greater than sufficient for this mannequin’s wants.

The subsequent drawback to handle is the truth that the GPU and reminiscence chips do not run on +3.Three or +12 voltages: the GDDR5 chips are 1.35V and the AMD GPU requires 1.172V. That means the provision voltages have to be dropped and punctiliously regulated, and this activity is dealt with by voltage regulator modules (VRMs, for brief).

We noticed related VRMs after we checked out motherboards and energy provide items, and so they’re the usual mechanism used right now. They additionally get a bit toasty after they’re working away, which is why they’re additionally (or hopefully additionally!) buried beneath a heatsink to maintain them inside their working temperature vary.

Just like with motherboard and CPUs, the quantity and kind (learn: high quality) of the VRMs has an impression on how steady the GPU is, when it is being overclocked. Included on this, is the standard of the general energy controlling chip.

This decade-old Radeon HD 6870 makes use of a CHIL CHL821401, which is a 4+1 part PWM controller (so it will probably deal with the Four VRMs seen above, plus one other voltage regulation system); it will probably additionally hold observe of temperatures and the way a lot present is being drawn. It can set the VRMs to alter between one in every of three completely different voltages, a function that is used closely in trendy GPUs as they change to a decrease voltage when idling, to save lots of energy and hold warmth/noise down.

The extra energy the GPU requires, the extra VRMs and the higher the PWM controller will have to be. For instance, in our evaluate of Nvidia’s GeForce RTX 2080, we pulled off the cooling system to have a look at the circuit board and the elements:

You can see a battery of ten VRMs operating down the complete peak of the cardboard, to the precise of the GPU; the likes of EVGA provide graphics playing cards with practically double that quantity! These playing cards are, after all, designed to be closely overclocked and when they’re, the ability consumption of the graphics card might be properly over 300W.

Fortunately, not each graphics card on the market has insane vitality necessities. The greatest mid-range merchandise on the market proper now are between 125 and 175W, which is roughly in the identical ballpark as our Radeon HD 6870.

The ins and outs of a graphics card

So far we have regarded on the digital elements on the circuit board and the way energy is provided to them. Time to see how directions and knowledge are despatched to the GPU, and the way it then sends its outcomes off to a monitor. In phrases, the enter/output (I/O) connections.

Instructions and knowledge are despatched and obtained through the PCI Express connector we noticed earlier than. It’s all accomplished by way of the pins on the lengthy part of the slot connector. All of the transmit pins are on one facet, and the obtain pins on the opposite.

PCI Express communication is completed utilizing differential signalling, so two pins are used collectively, sending 1 bit of information per clock cycle. Forever, pair of information pins there are an extra 2 pins for grounding, so a full set includes 2 ship pins, 2 obtain pins, and Four floor pins. Together, they’re collectively referred to as a lane.

The variety of lanes utilized by the system is indicated by the label x1, x4, x8, or x16 – referring to 1 lane, Four lanes, and many others. Almost all graphics playing cards use 16 lanes (i.e. PCI Express x16), which implies the interface can ship/obtain as much as 16 bits per cycle.

The sign sending the info run at Four GHz in a PCI Express 3.Zero connector, however knowledge might be timed for sending twice per cycle. This provides a theoretical knowledge bandwidth of Four GHz x 2 per cycle x 16 bit = 128 Mbits/sec or 16 MB/sec every approach.

It’s really lower than that, as a result of PCI Express signalling makes use of an encoding system that sacrifices a few of bits (round 1.5%) for sign high quality. The very newest model of the PCI Express specification, 4.0, doubles this to 32 GB/s; there are two extra specs in improvement that multiply this once more by 2 respectively.

Some graphics playing cards, like our HD 6870, have a further connector, as proven beneath:

This enables you to couple two or extra playing cards collectively, in order that they will share knowledge shortly when working as a multi-GPU system. Each vendor has their very own identify for it: AMD calls theirs CrossFire, Nvidia does SLI. The former does not use this connector anymore, and as an alternative simply does every part by way of the PCI Express slot.

If you look again up this web page on the picture for the GeForce RTX 2080, you may see that there are two such multi-GPU connections — that is Nvidia’s newer model, referred to as NVLink. It’s largely focused in the direction of skilled graphics and compute playing cards, somewhat than basic gaming ones. Despite the efforts of AMD and Nvidia to get multi-GPU programs into mainstream use, it isn’t been overly profitable, and lately you are simply higher off getting the perfect single GPU which you could afford.

Every desktop PC graphics may even have at the least one technique to attach a monitor to it, however most have a number of. They do that as a result of screens are available in every kind of fashions and budgets, which implies the cardboard might want to assist as a lot of these as attainable.

Our stripped down Radeon has 5 such outputs:

Have a glance:

As properly supporting as many monitor sorts as attainable, having a number of output sockets additionally means you possibly can connect a couple of show to the graphics card. Some of this monitor juggling will get dealt with by the GPU itself, however generally an additional chip is required to a little bit of sign sleight of hand. In our card, it has a Pericom P13HDMI4 HDMI change to do a few of this:

That tiny little chip converts HDMI knowledge, which comprises digital video and audio streams, into the picture-only indicators for the DVI sockets. The specification of those connections is much more vital lately, due to adjustments in how we’re utilizing our screens.

The rise of esports has the monitor trade steering in the direction of ever greater refresh charges (the variety of occasions per second that the monitor redraws the picture on the display screen) — 10 years in the past, the overwhelming majority of screens had been capped at 60 or 75 Hz. Today, you will get 1080p screens that may run at 240 Hz.

Modern graphics playing cards are additionally very highly effective, and lots of are able to operating at excessive resolutions, similar to 1440p and 4K, or provide excessive dynamic vary (HDR) outputs. And so as to add to the lengthy listing of calls for, plenty of screens assist variable refresh fee (VRR) expertise; a system which prevents the monitor from attempting to replace its picture, whereas the graphics card remains to be drawing it.

There are open and proprietary codecs for VRR:

To be capable to use these options (e.g. excessive resolutions, excessive and variable refresh charges, HDR), there are Three questions that must be answered: does the monitor assist it? Does the GPU assist it? Does the graphics card use output connectors able to doing it?

If you head off and purchase one of many newest playing cards from AMD (Navi) or Nvidia (Turing), here is what output programs they assist:

Manufacturer AMD Nvidia
DVI Dual-Link Digital Dual-Link Digital
1600p @ 60Hz, 1080p @ 144Hz 1600p @ 60Hz, 1080p @ 144Hz
DisplayPort 1.4a (DSC 1.2) 1.4a (DSC 1.2)
4K HDR @ 240Hz, 8K HDR @ 60Hz 4K HDR @ 144Hz, 8K HDR @ 60Hz
HDMI 2.0b 2.0b
4K @ 60Hz, 1080p @ 240Hz 4K @ 60Hz, 1080p @ 240Hz
VRR DP Adaptive-sync, HDMI VRR, FreeSync DP Adaptive-sync, HDMI VRR, G-Sync

The above numbers do not paint the complete image, although. Sure, you possibly can fireplace 4K frames at over 200 Hz by way of the DisplayPort connection to the monitor, nevertheless it will not be with the uncooked knowledge within the graphics card’s RAM. The output can solely ship so many bits per second, and for actually excessive resolutions and refresh charges, it isn’t sufficient.

Fortunately, knowledge compression or chroma subsampling (a course of the place the quantity of colour data despatched is decreased) can be utilized to ease the load on the show system. This is the place slight variations in graphics card fashions could make a distinction: one may use a regular compression system, a proprietary one or a variant of chroma subsampling.

20 years in the past, there have been large variations within the video outputs of graphics playing cards, and also you had been usually compelled to make the selection of sacrificing high quality for velocity. Not so right now… phew!

All that for simply graphics?

It may appear only a wee bit odd that a lot complexity and price is required to only draw the photographs we see, after we’re taking part in Call of Mario: Deathduty Battleyard. Go again to close the beginning of this text and look once more at that ATi 3D Charger graphics card. That GPU may spit out as much as 1 million triangles and colour in 25 million pixels in a second. For a equally priced card right now, these numbers soar by an element of over 2,000.

Do we actually want that type of efficiency? The reply is sure: partly as a result of right now’s avid gamers have a lot greater expectations of graphics, but in addition as a result of making real looking 3D visuals, in real-time, is tremendous exhausting. So while you’re hacking away at dragons, zooming by way of Eau Rouge into Raidillon, or frantically dealing with a Zerg Rush, simply spare just a few seconds to your graphics card — you are asking a whole lot of it!

But GPUs can do extra than simply course of photos. The previous few years has seen an explosion in using these processors in supercomputers, for complicated machine studying and synthetic intelligence. Cryptomining grew to become insanely fashionable in 2018, and graphics playing cards had been excellent for such work.

The buzzword right here is compute –– a area usually within the area of the CPU, the GPU has now taken over in particular areas that require huge parallel calculations, all accomplished utilizing excessive precision knowledge values. Both AMD and Nvidia make merchandise geared toward this market, and so they’re practically at all times sporting the most important and costliest graphics processors.

Speaking of which, have you ever ever questioned what the center of a $2,500 graphics card appears like? Gamers Nexus should have been curious, too, as a result of they went forward and pulled one aside:

If you are tempted to do the identical with yours, please watch out! Don’t overlook that every one these digital elements are fairly fragile and we doubt any retailer will change it, in the event you mess issues up.

So whether or not your graphics card value $20, $200, or $2,000, they’re all basically the identical design: a extremely specialised processor, on a circuit board full of supporting chips and different digital elements. Compared to our dissection of a motherboard and energy provide unit, there’s much less stuff to drag aside, however what’s there’s fairly superior.

And so we are saying goodbye to the stays of our Radeon HD 6870 graphics card. The bits will go in a field and get saved in a cabinet. Somewhat of an ignominious finish to such a marvel of computing expertise, that wowed us by making unbelievable photos, all made attainable by way of using billions of microscopic transistors.

If you have bought any questions on GPUs generally or the one you are utilizing proper now in your pc, then ship them our approach within the feedback part beneath. Stay tuned for much more anatomy sequence options.

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