Could the hd7970 have been designed with 40 ROPs?

[-Slacker-]

Could it have had 40 ROPs instead of 32, or does it need to follow a special format that's dependent on the memory bus - like how the 384bit gtx480/580 had 48 ROPs, the 320bit 470/570 had 40 ROPs and the 256 bit parts had 32?

I see that each ROP on tahiti is arranged in clusters of 4 ROPS, each ROP corresponding to a cluster of 64 shaders. Could this arrangement be changed so that the gpu would retain its shader count, but incorporate more ROPs up to 40 (maybe even 36)?

If not, would doubling the number of ROPs - since that seems to work mathematically- increase the die too much?

I'm asking after hearing speculation that the hd7970 is bottlenecked in this regard, even though each individual ROP has been improved since the last generation.

 

[-Slacker-]

Lol I guess it was a stupid question

 

[Olikan]

no GPU is ROP starved, since 8 years ago...IIRC

 

[-Slacker-]

Then why do they put more and more on them?

 

[Meaker10]

Because they give them enough?

You can't just have floating resources, they need to be structured and linked into everything else.

 

[Concillian]

no GPU is ROP starved, since 8 years ago...IIRC

not so sure about starved, but 7850 and 7870 OCing is significantly better than would be expected given the loss of shaders, TMU and bandwidth vs. the 79xx cards.

This has to be either due to ROP or cache to shader / TMU ratio. People have been assuming it's ROP, I think, since they have the same ROP performance as a 79xx at the same speed.

 

[Olikan]

Then why do they more and more on them?

because ROPs aren't god like performers, they need balance...if you put the same ROPs of the cypress in tahiti, tahiti will be ROPs starved

not so sure about starved, but 7850 and 7870 OCing is significantly better than would be expected given the loss of shaders, TMU and bandwidth vs. the 79xx cards.

the 78xx series is a game oriented card, unlike the 79xx

from what i have read, the 79xx series have TMU and caches problems, that were fixed at 77xx and 78xx

 

[-Slacker-]

^But are the 78xxs gaming cards because the fixed issues or...?

Do they have different compute shaders?

 

[Olikan]

fixed issues.....and gpgpu

 

[Concillian]

How does how "game oriented" a card is matter in terms of the absolute that you put forth that NO video card has been ROP starved in several generations?

Starved is a pretty ambiguous word, but still there is at least some evidence that 7900 series cards would significantly benefit from more ROP performance. Whether or not that translates to "starved" or not is obviously debatable, and probably a poor choice of words on whoever chose to use that term initially, but there is evidence that ROP performance may be one of the two main things holding back the 79xx from being as effiicient per shader in games as the 77xx and 78xx cards are.

 

[ViRGE]

On a technical level it's possible, but given the construction of the crossbar it would be difficult. 40 ROPs wouldn't map well to the crossbar, so for all the trouble in doing so 48 ROPs would be easier in the end.