It may end up being called Amethyst instead

Oct 27, 2014 04:48 GMT  ·  By

The Tonga graphics processing unit may not have made it to products other than the Radeon R9 285 graphics card yet, and last we heard the R9 285X was still canceled, but a new report suggests that the chip isn't out of the running yet.

Based on the YouTube video embedded below, we can at least say for sure that the Radeon R9 M295X exists, essentially the mobile version of what the R9 295X would have been.

AMD hasn't confirmed that Tonga (or Tonga XT) is really the architecture we're looking at, and there is some reason to believe that the chip may be called Amethyst XT instead.

Whatever the case is, the chip looks to be quite promising, even though we can't, at present, promise that it's superior to the NVIDIA GeForce GM204 in the GTX 980. Not that a comparison between a mobile (laptop) chip and a desktop card is all that fair.

It's still better than the GeForce GTX 780M though. That's what CineBench tests showed. But in the absence of 3DMark or other benchmarks, we can't be 100% sure that it's really better.

The Radeon R9 M285X GPU specifications

Whether or not it's a Tonga XT or Amethyst XT chip, the graphics processing unit has 2,048 stream processors, as well as 4 GB of GDDR5 VRAM and a 256-bit interface controlling that memory.

The frequency of the chip is 800 MHz, and we can only assume that this is either the PGU Boost maximum clock or that the mobile GPU forgoes dynamic overclocking altogether. Unlikely, but there it is.

Meanwhile, the GDDR5 VRAM works at 1,375 MHz (5,500 MHz effective) and the bandwidth is of 176 GB/s. On a related note, the number of TMUs (texture mapping units) and ROPs (raster operating units) is 128 and 32, respectively.

Comparisons

The Radeon R9 M295X Tonga XT / Amethyst XT GPU is better than the R9 290X Neptune XT by a fair bit, since the latter has only 1,280 Stream Processors and a memory clock of 1,200 MHz (4,800 MHz effective). Sure, the R9 M290X has a clock of 900 MHz for the GPU, but the slower memory and TMU / ROP count (80 / 32) offset that. The Memory bandwidth is 153.6 GB/s by the way.

So while the R9 M295X is slower than desktop video cards, it beats everything else AMD has on the laptop market right now.

Sadly, we can't really make an informed guess about how the new (or upcoming) AMD chip does against NVIDIA's lineup, especially the GeForce GTX 980M and the other Maxwell-based laptop processors.