AMD (NYSE: AMD) already launched a video card featuring the Tonga GPU in the Radeon R9 285, but there hasn’t been any word on when the fully-unlocked Tonga XT GPU will be available. While there may not be much information regarding any upcoming cards, the GPU itself has been detailed in a new leak that shows that it comes with a 384-bit wide GDDR5 memory interface and not the 256-bit interface as previously rumored.
The R9 285 has a 256-bit interface, but the leak shows that the die can be placed on a bigger package that can fully utilize the memory bus. What this means for upcoming video cards is that they will have 50% more memory bandwidth than the R9 285. AMD went a similar route with Tahiti LE on the HD 7870, so it is entirely feasible that the vendor is looking to do the same with Tonga. It is unclear whether the GPU will come with 32 or 48 ROPs, but what is evident is that it packs 128 TMUs.
The stream processor count on the 28 nm Tonga XT is still 2,048, but the cores are second-generation GCN 1.2 that offer much more performance per Watt, which could allow AMD to mount a significant challenge to Nvidia’s Maxwell architecture. Another key area that AMD is looking to address with Tonga XT is flexible context switching at the GPU level, which would bring virtualization and will be the precursor to AMD’s goal of HSA.
The rumors suggested that AMD was considering launching a Radeon R9 285X with the Tonga XT GPU, but there has been no word whether the silicon vendor is still on track to deliver the video card, or is focusing its attentions elsewhere to counter the threat of Maxwell. Nvidia clearly caught AMD off-guard with the GTX 980 and the GTX 970, and with both cards now available worldwide, AMD has to mount a counter offensive, and fast.