Is Bonaire a weak link in GCN.?

[Averagejoe]

If this is not the correct forum for this topic my bad.


I wanted to ask something,in GCN all GPU perform according to their flops number,7770 > 7750 7870 > 7850 7970 > 7950.

But with Bonaire i found on AMD page that is 1.79 TF,but the benchmarks i have see comparing it with the 7850,it basically loss in all test.

Since the 7850 is tag by AMD to be 1.76 TF i wonder why Bonaire 7790 doesn't beat it or at least tie with it,i know flops are not everything,but on GCN the one with most flops perform better.

What do you people think could be holding back the 7790 from beating the 7850.?

ROP,bandwidth limitation.?

Or just the simple fact that 16 CU at 860mhz perform better than 14 CU at 1ghz.

 

[kalelovil]

The 7850 has 72% higher peak pixel fillrate (16 ROPs at 1Ghz vs. 32 ROPs at 0.86Ghz) and 60% higher memory bandwidth.

 

[lanek]

The difference for Tflops is in the clock speed ( at least on the stock version ).

- 7790 = 896SP @ 1000mhz
- 7850 = 1024SP @ 860mhz.. push the 7850 to 1ghz and you get more Tflops, and ofc the performance difference between both is bigger.

And as explained higher, the 7850 have higher spec all around.

 

[Silent_Buddha]

Which is why it's interesting that the 7790 is so close to the 7850 in many cases. The argument being that it's a better balance of resources.

Regards,
SB

 

[lanek]

I tend to believe, the clock speed is not completely stranger to that too. ( + a better balance ).

 

[jimbo75]

It's not that bad - http://www.anandtech.com/bench/product/778?vs=776

On a quick once-over it looks like the 7850 is ~20% faster on average. The 7850 probably has a little more bandwidth than it needs, while the 7790 has a little less than it needs. A 192-bit bus would likely be perfect for both.

Going forward, AMD is clearly committed to reducing bandwidth requirements with GCN. Bonaire is proof of what can be achieved with a smaller die and a lot less power. This strategy should put AMD in a strong position in mobile over the next few years (it might work against them in desktop, however).

 

[Averagejoe]

That answer my question thank you all.