Sunday, June 6th 2021

Reference Liquid-Cooled Radeon RX 6900 XT Listed, Possibly the RX 6900 XTX, with Faster Memory

To preempt NVIDIA's GeForce RTX 3080 Ti launch, AMD had worked with its partners to release a refreshed Radeon RX 6900 XT based on a swanky new ASIC internally dubbed "XTXH." This is essentially the highest bin of the "Navi 21" silicon that allows 10% higher clock speeds over the standard RX 6900 XT. Our testing of one such card, the ASRock RX 6900 XT OC Formula, showed that the XTXH is able to trade blows with the RTX 3090, making it competitive with the RTX 3080 Ti. Interestingly, there seemed to lack a reference design "made by AMD" card based on this silicon. Turns out, AMD had other plans. This card was earlier believed to be the "Radeon RX 6900 XTX," when it was first leaked in April, but turns out, that AMD is allowing partners to simply call this the RX 6900 XT.

The reference design card uses a liquid-cooled design. The card itself is two slots thick, and about the size of the reference Radeon RX 6800, but two coolant tubes emerge from its top, which head to a 120 mm x 120 mm radiator. This is a purely liquid-cooled card, with no secondary air-based cooling, like the ASUS ROG Strix LC RX 6900 XT. The only sources of noise are the AIO pump-block, and the single included 120 mm fan. Besides 10% higher GPU clocks, the reference design card has an ace in the hole that custom-design XTXH cards lack—faster memory.
A listing of a Sapphire-branded reference liquid-cooled card on Brazilian online store Kabum claims that the card comes with a memory clock speed of 18 Gbps GDDR6. Samsung has been mass-producing 18 Gbps-rated GDDR6 memory chips (which are not GDDR6X), since 2018, so it's likely that AMD secured itself some volume to send to its reference-design OEM, PC Partner. At 18 Gbps, the memory bandwidth shoots up to 576 GB/s, from 512 GB/s on the RX 6900 XT.

The card's engine boost frequency is listed as 2435 MHz, which is in the league of other XTXH cards, so it's not like the faster memory is compensating for lower engine clocks. What's interesting, though is that the pictures reveal that the card makes do with just two 8-pin PCIe power connectors—a configuration rated for 375 W—while every custom-design XTXH card uses a triple 8-pin configuration rated for 525 W. Kabum claims the card will ship from 30th June, 2021.
Sources: Kabum, Video Cardz
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14 Comments on Reference Liquid-Cooled Radeon RX 6900 XT Listed, Possibly the RX 6900 XTX, with Faster Memory

#1
Soulander
Wow, this store is called Kabum! My (Kabum)account is bugged for unknown reasons. Their support sucks!

Edit: price is around of US$4000(green).
pre-venda = pre-order
lista de desejos = wishlist
shipping after June 26
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#2
Caring1
375W to reduce heat, as without a fan on the PCB these will cook themselves. (IMO)
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#3
RealKGB
Ooh, tempting.
Given that:
- macOS 11.4 Big Sur now supports the 6900 XT
- It looks short enough to fit in my case (I have a ~280mm limit)
- It has a 120mm radiator, though perhaps this can be switched to 140mm? 140 would be preferable as it has larger surface area.
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#4
Xex360
Is there a reason why RDNA2 memory speed is limited to 2150MT/s.
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#5
xkm1948
I am having major flash backs to my previous FuryX.

Cool and all, I hope they gave it 5yrs warranty on those AIO equipped GPUs.
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#6
beedoo
So, if my normal 6900 XT is under-volted and running at 2441Mhz in Control (the game), 'that mean it's likely using an XTXH die?
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#7
Vader
Caring1375W to reduce heat, as without a fan on the PCB these will cook themselves. (IMO)
Not if the coldplate contacts every important bit
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#8
ZoneDymo
Xex360Is there a reason why RDNA2 memory speed is limited to 2150MT/s.
This, never understand artificial oc limits, it's scummy and anti consumer.

The product does looks sexy but it will be as pricey as unavailable.

It's funny to.me that amd releases high end competitive gpus right when affordable gpus are wanted.
They could have potentially gotten their cards in the hands of gamers, giving amd some.mindshare in that space while nvidia would sell to miners
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#9
turbogear
Like the reference 6900XT they made this one also only with 2xPCIe power connector so limited to 375W. :oops:
It would be interesting to see how high this one clocks compared to other XTXH models.

As I own 6900XTU Liquid Devil Ultimate, I know that XTXH cards like more power and good cooling to OC higher.
So not sure how high these can clock with only small radiator to cool it and with 375W power limit.
My XTXH is set at 415W Core Power and 400A TDC and runs 2750MHz@1175mV stable. With lower power target, this frequency was not stable in 3DMARK.
In games like Cyberpunk though Core power draw is in range of 330-350W at this OC.
My card has EK block factory fitted but hotspot temperature were still hitting 92°C even with my custom loop with 3 rads that I have for cooling it together with 5900X.
I changed from standard paste to Liquid Metal and now hotspot temperatures remain below 78°C.
The VRM temperatures at 415W Core stress test remains in range of 55°C. The cold plate on EK block covers these as well.

The 18 Gbps is really interesting. If that is true, then this will mean memory running at 2250MHz. :D
That is the max value that can be set under Radeon software for the XTXH cards.
Usually on many 6800XT/6900XT cards the Time Spy score actual gets worst if memory is clocked higher than 2120MHz which is the same case on my XTXH card. So setting it to 2250MHz does not make sense on my card as performance is degraded.

It would be interesting to look into the Bios what setting AMD is using for this reference card to run memory that high without actually loosing performance.
Hopefully somebody who buys this card uploads his Bios to TPU database. :D
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#10
Bruno Vieira
beedooSo, if my normal 6900 XT is under-volted and running at 2441Mhz in Control (the game), 'that mean it's likely using an XTXH die?
No its a different die and sold only on selected cards. Its not random, they can OC core past 3Ghz given the new clockgen and memory past 2150. And many people tried to bios flash from 6900xt to 6900xtx and bricked the card, hard to flash back the previous bios
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#11
jesdals
OMG I slept for a year and its april 1. again...
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#12
watzupken
I don't see the need for this card to be honest. If AMD launched the XTX version just to compete with RTX 3080 TI, the upgrade is not even in the same league. On the RTX 3080 Ti, there are tangible hardware improvements, while the XTX comes with slightly faster memory and clock speed, which I don't think is going to make a significant difference in performance. AMD have proven that RDNA2 is highly competitive at the high end, and I think that's all they need to do, while focusing on future products.
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#13
Minus Infinity
Oh boy can't wait to see if this is the first $5K non-existent gaming card in Australia. theBradRad will buy one and still play his games at a pathetic 1080p. He already has 3090 and won't do 1440p or let alone 4K.
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#14
64K
Minus InfinityOh boy can't wait to see if this is the first $5K non-existent gaming card in Australia. theBradRad will buy one and still play his games at a pathetic 1080p. He already has 3090 and won't do 1440p or let alone 4K.
That's pretty wild. The high end cards are good for at least 1440p unless that guy is just trying to get extremely high frame rates by using 1080p.
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