AMD Radeon RX 7900 XTX Reference Design PCB and Cooler Detailed

[btarunr]

AMD Radeon RX 7900 XTX reference-design isn't a first-party product with limited availability like the NVIDIA Founders Edition; but rather a classic reference-design that's sold by AMD's add-in board partners under their marquee (without sticking their own labels on the product). AMD and its partners internally refer to reference-design cards as "MBA cards" (made by AMD cards). The company gave us a technical overview of the reference-design PCB. As with every reference AMD PCB for the past several generations, the RX 7900 XTX PCB has a premium selection of components. The card uses an expensive 14-layer PCB with 4 additional layers of 2-oz copper. 14-layer PCBs are typically used with enterprise-grade products, and graphics cards typically tend to have PCB layer counts of around 10. The PCB also uses ITEQ IT-170GRA epoxy and laminate materials, which enable a glass transition temperature (Tg) of 175 °C (no, the GPU won't get anywhere near as hot).

The reference-design RX 7900 XTX PCB draws power from two 8-pin PCIe power connectors. With the typical board power of the RX 7900 XTX rated at 355 W, this falls inside the 375 total power-draw capability when you add up the 150 W input from the two connectors, and 75 W from the PCIe slot. AMD worked to minimize power-draw spikes at least from the PCIe slot. Excursions, if any, should be localized to the 8-pin power connectors. The card features 20-phase VRM solution, using "high efficiency" DrMOS power-stage phases (could be very high current). The "Navi 31" GPU is surrounded by 12 GDDR6 memory chips given the GPU's 384-bit memory interface. Two of these memory pads could end up unused on the RX 7900 XT, which has a 320-bit memory interface. Display outputs of the RX 7900 series include two standard-size DisplayPort 2.1, one USB type-C with DisplayPort passthrough; and one HDMI 2.1a.



The cooling solution features an aluminium fin-stack heatsink that's ventilated axially by three fans that offer individual speed control and come with intake air temperature sensors. The cooler shroud and backplate are made of die-cast aluminium. The main heatsink uses a large aluminium fin-stack to which heat is drawn by a vapor-chamber plate. The vapor-chamber and base-plate pull heat from the GPU, memory chips, and VRM. A secondary heatspreader pulls heat from other minor heat sources and structurally reinforces the card. AMD says that the vapor chamber plate is 10% larger than the one in the RX 6950 XT RDNA2 reference-design. The company is introducing a newer thermal interface material (TIM) for the GPU and memory chips, and an "ultra soft" thermal pad for the VRM MOSFETs.

It turns out that the RX 7900 XTX reference design card is physically larger than the RX 7900 XT reference design (if it does exist in production). The reference RX 7900 XTX is 28.7 cm long and 12.3 cm tall; whereas the RX 7900 XT is 27.6 cm long, and 11.3 cm tall, making it closer to being a standard "full-height" add-in board. Both cards at 2.5-slot thick. The RX 7900 XT is compact as the cooler has to deal with a 15% lower typical board power of 300 W compared to 355 W for the RX 7900 XTX.

View at TechPowerUp Main Site

 

[Valantar]

@btarunr Based on the renders in AMD's slides here, they can't be using the same PCB - the pictured PCB is too tall (above the display outputs) to fit within the shroud of the smaller 7900 XT as rendered in the first slide. It would also be unprecedented for AMD to not have a reference design for a second-tier SKU - for RDNA2 the first card without one was the 6600 XT, a seventh tier card (and third in terms of silicon).


Other than that, this looks like a good design - here's hoping it holds up in practice too!

I have to say it's rather interesting to not use the same PCB design for a flagship and second-tier GPU, especially when based on the same GPU die. I wonder how they worked that out economically - if I were to guess, I'd say the reference 7900 XT PCB is pin-compatible with at least one further SKU down the stack.

 

[MarsM4N]

"Premium die-cast aluminum shroud"

Dam, that's great. From the images I expected it to be plastic. Aluminum is just more premium, plus better for thermals. And it doesn't burn, lol.

"The card uses an expensive 14-layer PCB with 4 additional layers of 2-oz copper."

MSI is also using 2oz copper in some of their mainboards. So guess it doesn't hurt.

"6-Layer Server Grade PCB: 6-layer PCB with 2oz thickened copper provides higher performance and long-lasting system stability without any compromise." MSI

 

[ZoneDymo]

that hole spacing seems quite a bit bigger then it was previously

 

[HairyLobsters]

How would an aluminum shroud help with thermals if there's nothing connecting it thermally to the rest of the card?

 

[ZoneDymo]

How would an aluminum shroud help with thermals if there's nothing connecting it thermally to the rest of the card?

Sure, Aluminium is a good heat absorber, so also radiant heat it will absorb and dissipate to the outside unlike plastic which will just trap it inside.

 

[ARF]

How would an aluminum shroud help with thermals if there's nothing connecting it thermally to the rest of the card?

Well, there is always an influence but I guess your question is about how much.
Of course, if the shroud was made of copper or another material that is more conductive than aluminium, things would be better.

Have you parked your car with the windshield oriented towards a building during colder periods when the temperature drops below 0°C?
You would see that the building heats the windshield and it remains frost free, unlike the other car screens which get frozen.

 

[MarsM4N]

How would an aluminum shroud help with thermals if there's nothing connecting it thermally to the rest of the card?

Aluminum is thermal conductive while plastic is more like a insulator. Sure, the thermal difference likely is minimal, but it's there.

 

[QuietBob]

It looks like an efficient design. I just hope that AMD's claims of "up to 54% more perf/watt than RDNA2" will bear out. I'm all for cost-effectiveness over raw performance, especially one that comes with absurd energy consumption. I might be tempted to get the XTX if it shows high efficiency at lower power levels.

Besides, my case limits me to 30.5cm for the graphics, and I don't feel like looking for a new one. This reference design may just be the right fit at 28.7cm.

 

[ymdhis]

Dam, that's great. From the images I expected it to be plastic. Aluminum is just more premium, plus better for thermals. And it doesn't burn, lol.

They can't use plastic because Plastic Aluminum Shrouds are banned in the EU along with the plastic straws and toothpicks. They have to use premium aluminum made out of actual aluminum. It's why videocards cost 50% more in the EU.

 

[Blue4130]

They can't use plastic because Plastic Aluminum Shrouds are banned in the EU along with the plastic straws and toothpicks. They have to use premium aluminum made out of actual aluminum. It's why videocards cost 50% more in the EU.

I thought only disposable single use plastics were banned? Surely a GPU doesn't fall into the same category as spoons and straws.

 

[mechtech]

hmmmm specs and built quality looks great on the slides.............................be even nicer if it translated to a 5yr warranty.............

 

[Valantar]

I thought only disposable single use plastics were banned? Surely a GPU doesn't fall into the same category as spoons and straws.

They most definitely don't. Single-use plastics are banned, products made from plastic are not. That would be ... difficult, to say the least. It would probably ban, oh, 50% of products on the market?

 

[Chaitanya]

Dam, that's great. From the images I expected it to be plastic. Aluminum is just more premium, plus better for thermals. And it doesn't burn, lol.



MSI is also using 2oz copper in some of their mainboards. So guess it doesn't hurt.

"6-Layer Server Grade PCB: 6-layer PCB with 2oz thickened copper provides higher performance and long-lasting system stability without any compromise." MSI

Whole 2oz copper trend was started by Gigabyte and slowly it has caught up among other motherboard makers.

 

[trsttte]

I wish a company could release detailed pictures like these without using meaningless words/expressions like "high performance", "high efficiency" or, and perharps the worst of them all, "premium". What does that even mean?

How is a 14 layer high performance pcb different from a regular 14 layer pcb? Do you mean to say you've been selling shit for the past years? (of course not, those were also high performance/premium/whatever). God damn marketing guys...

They most definitely don't. Single-use plastics are banned, products made from plastic are not. That would be ... difficult, to say the least. It would probably ban, oh, 50% of products on the market?

Even some single use plastics are not banned because there's simply no viable alternative (medical stuff being a big example). Only common stuff like straws, forks, etc.. that are very easily replaceable even though some people like to make a big fuss about it.

 

[HisDivineOrder]

The 7900XTX being $1k is surprisingly making it the most interesting new GPU (to me) in a while. I hope it can deliver the performance it seems to be capable of. Everytime people talk about the 4090, I wonder why. If you have to make your GPU $1600+ to innovate, you basically gave up trying imo.

 

[N/A]

The surprising part is when it can actually be acquired at that price and remain in stock.

 

[TechLurker]

I wish more cards from AIBs used aluminum in their top-end models, such as Sapphire's Nitro+, Toxic, and Atomic ranges, or PowerColor's Liquid Devil, Red Devil, and Devil 13 (if ever brought back) variants of the top end SKU (X900 XT or X900 XTX), etc. I mean, users are already paying for premium performance, just throw in aluminum cladding to complete the statement.

 

[Animalpak]

High new tech here, highest new tech there...

But still no one who is committed to decreasing or eliminating coil whining

 

[Valantar]

I wish a company could release detailed pictures like these without using meaningless words/expressions like "high performance", "high efficiency" or, and perharps the worst of them all, "premium". What does that even mean?

How is a 14 layer high performance pcb different from a regular 14 layer pcb? Do you mean to say you've been selling shit for the past years? (of course not, those were also high performance/premium/whatever). God damn marketing guys...

I think the argument being made is that any 14-layer PCB is a high performance PCB, as compared to lower layer count, lower performance PCBs (though the use of premium PCB materials is likely also a part of this, it's rather unlikely for anyone to make a 14-layer PCB with lower grade materials to begin with).

I honestly don't see any of this language as problematic - it's so broad that these are just general statements about the overall characteristics of the product. "High performance" - well, yes, it's a GPU meant to compete at the very peak of performance. High efficiency? Yes, they claim up to +54% perf/W - specifically. Premium means premium, as in expensive, using high grade materials, etc. If they aren't allowed to use very general descriptors like these you might as well ban the use of adjectives in advertising.

 

[Dyatlov A]

Dam, that's great. From the images I expected it to be plastic. Aluminum is just more premium, plus better for thermals. And it doesn't burn, lol.



MSI is also using 2oz copper in some of their mainboards. So guess it doesn't hurt.

"6-Layer Server Grade PCB: 6-layer PCB with 2oz thickened copper provides higher performance and long-lasting system stability without any compromise." MSI

yeah, the card looks cheap plastic for me as well, i am glad if it is aluminium, but i will still need to explain guests, that is actually aluminium

 

[Valantar]

yeah, the card looks cheap plastic for me as well, i am glad if it is aluminium, but i will still need to explain guests, that is actually aluminium

Judging materials from pictures, especially renders, is essentially impossible. IRL is another thing entirely.