All you need to know about AMD's 'missing' 7800 XT and 7700 XT GPUs

AMD rolled out its Radeon RX 7900 XT and XTX GPUs last year. Then came the RX 7600 in May. But here we are towards the end of June and there's no word on AMD filling out its RDNA 3 range with the 7800 XT and 7700 XT, plus presumably non-XT versions. So, what exactly is going on?

The first thing to note is that the RX 7800 and 7700 cards aren't actually all that late. The RX 6700 XT launched in March 2021, so the typical expectation would have been for a 7700 XT in March this year. At worst, then, the 7700 XT is arguably a few months late.

As for the 7800 XT, that's a bit more complicated. AMD changed up its branding with the 7900 XT and 7900 XTX. When RDNA 2 was launched at the end of 2020, the 6900 XT was the top card, with the 6800 XT directly below it and based on the the same Navi 21 GPU.

So, you could argue the 7800 XT is already here, it's just called the 7900 XT. But then, of course, we're still missing a replacement for the plain non-XT RX 6800. And the aforementioned 6700 XT and 6700 non-XT.

However you slice it, then, there's a big, fat hole in the middle of the RDNA 3 lineup. Enter the latest round of rumours. One major discussion point involves so-called 'leaks' claiming that the 7800 XT will actually be based on the same Navi 31 GPU as the existing 7900 XT and XTX.

That certainly makes sense and would not actually be a surprise. Whether a mooted 7800 XT is a replacement for the last-gen 6800 XT or the non-XT 6800, being based on the biggest available GPU would be in line with AMD's previous approach.

As it happens, AMD already has just such a reworking of Navi 31 available in the Radeon Pro W7800. That's a professional GPU, not a gaming card. But it uses a cut-down Navi 31 GPU with 70 CUs and 4,480 shaders. Lest you have forgotten, the 7900 XT has 84 CUs and 5,376 shaders while the 7900 XTX rocks the full 96 CUs and 6,144 shaders.

So AMD has something ready to go that could fill the 7800 XT role. What about the 7700 XT? That's where Navi 32 comes in. It's also where things become a bit speculative. Current best information indicates that Navi 32 is a chiplet design, like Navi 31, but with a smaller graphics die and just four rather than six MCDs, the latter being those smaller chiplets containing cache and memory controllers.

Just such a GPU was recently spotted in a display of silicon AMD laid out during an interview with CEO Lisa Su. Four MCDs would make a 7700 XT 256-bit in terms of memory bus width, but one of the four MCDs could be a dummy inserted for packaging purposes. A three-MCD arrangement would deliver a 192-bit bus and allow for a 12GB 7700 XT card, which is what we are expecting.

Anyway, Navi 32 is generally thought to rock either 60 or 64 compute units, which would be the upper limit for a 7700 XT card, though some rumours have the 7700 XT using a cut-down Navi 32 GPU with just 54 CUs. Some rumours have indicated it may have as few as 48 CUs

Indeed, there could well be a 7800 non-XT with all 60 or 64 CUs activated. Such a GPU would then also use all four MCDs, run a 256-bit bus and offer 16GB of VRAM.

Incidentally, that 60 to 64 max CU count for Navi 32 also explains why it's unlikely to see service in the 7800 XT. It's just not enough CUs for that class of GPU. It would be barely, if any, faster than the old 6800 XT and its 72 RDNA 2-style CUs.

As for how any of these cards will perform, well, Navi 31 is a known quantity and indeed based on that W7800 pro card, Igor's Lab recently did the math and worked out that the mooted 7800 XT would be marginally quicker on average than the last-gen 6900 XT. Decent but not spectacular.

The 7700 XT, on the other hand, could be a bit more exciting. Remember, that estimated 7800 XT is based on 70 RDNA 3 CUs, while the 6900 XT has 80 old-style RDNA 2 CUs. I.e. fewer CUs but still slightly higher performance. 

The 7700 XT's CU count is more uncertain. The old 6700 XT has 40 RNDA 2 CUs. So even 48 RDNA 3 CUs should be a decent step, while 54 CUs would be even better. Of course, we've current no idea how high Navi 32 might clock, which is an important part of picture.

As, of course, is a launch date for any of these new GPUs. Unfortunately, there's no firm date. Most existing rumours suggest a Q3 launch, probably in September. Given the sparsity of leaked information, it certainly doesn't seem like new GPUs from AMD are imminent.  

The remaining question is why we haven't seen any of these new card yet. One possibility is that AMD has plenty of last-gen 6700, 6800 and 6900 derivatives left over that need shifting and so doesn't fancy adding to that pile with new GPUs.

The other possibility is technical issues with Navi 32. However, that wouldn't prevent a cut-down Navi 31-based 7800 XT from being launched. And as we've reported on numerous occasions, GPU sales are dire at the moment. So, the GPU glut theory seems like the more plausible explanation.

And that, folks, pretty much sums up the best available information on AMD's next GPUs. The TL;DR? Expect the 7800 XT and 7700 XT in September, with possible non-XT variants in tow.