Ok so, what's the smart thing to do after admiting that something I've posted was not true? Keep posting rumors, of course!
(After all, we all know that until AMD reveals the official specs and the cards are reviewed everything must be labeled as a rumor, right?)
This time the rumor is not about Fiji or the 390 cards but the 380/X, more specifically the Tonga chip that's supposed to be in the 380X.
Tonga will have 32CUs and a 384-bit bus.
Source1 (in german) Source2 (and the original one, because why name it the first )
All of this comes from the Tonga die shot that AMD revealed during the reveal of their Carrizo APUs:
Unless you're a hardware expert, this won't tell you anything. Don't worry, I'm no expert either.
Anyway, folks that do know about it recognized a couple of things: the 32 Compute Units (CU) and the 6 memory clusters. See the pic on this link to see them (sorry I can't hot-link it). Now, a little bit of explanation... which I had to look for it:
Memory: each memory cluster houses 4x 16-bit memory controllers for a total of 64-bits each cluster and a total 384-bit bus (4 mem controller x 16-bits each x 6 memory clusters = 384-bits bus).
CU: Each Compute Unit has 4 SIMD Engines with 16 Stream Processors (SP) and also 4 Texture Mapping Units (TMU). That means 1CU = 64xSP + 4xTMU.
Knowing that and given that AMD already used Tonga on the R9 285, rumors point that:
- R9 380_ A straigh rebrand of the R9 285 with 28 CUs, 1792 SPs and a 256-bit bus. The 256-bit bus means that it will have either 2 or 4Gb or GDDR5.
- R9 380X_ A full Tonga chip with the 32 CUs, 2048 SPs and a 384-bit bus. The 384-bit bus means that it will have either 3 or 6Gb or GDDR5.
Remember, take it with a pinch of salt.