Sapphire 7870 Overclock

PanStef

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Apr 19, 2014
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So I decided to overclock my gpu (sapphire radeon hd 7870 ghz edition). I overclocked using the catalyst suite, with its integrated overdrive feature.
Here's some info that might help you

I didn't use any voltage wteaking (i wanted to overclock without getting risky). I cranked up the speed by 50mhz packs.
The Furmark settings were 1280x1024 resolution, 8x MSAA, Dynamic Camera and Post FX at 1 minute duration. Also not that I did not see ANY artifacts.

#Stock core speed: 1000mhz
Furmark scorre:1817
Avarage fps: 30
Max: 33 Min: 27

#Setting power limit to +20%
Core speed: 1000mhz
Furmark:1819
Avarage fps: 30
Max: 33 Min: 27

#Core Speed: 1050mhz
Furmark score:1861
Avarage fps: 31
Max: 34 Min: 28

#Core Speed: 1100mhz
Furmark score:1888
Avarage fps: 31
Max: 36 Min: 28

#Core Speed: 1150mhz
Furmark score:1909
Avarage fps: 31
Max: 34 Min: 29

What concers me is that there is not that much of a perfomance boost for stock+150mhz, especially as far as the fps are concerned. The cpu is not a bottleneck, its utilization throughout the benchmark was about 9%-11%
What could be the problem or what should i try doing? Any tips are appreciated and i can provide further info as well as screenshots.

UPDATE

After I cranked the memory speed up I got scores as high as 2050. So the vram must be a bottleneck.
 
Solution
I think it's the memory bus that goes from the gpu's memory controller to the memory. AMD did things to improve this with later gpus like the R370 and finally with HBM memory.

I found with my HD-7850's the clock speed only makes more noise. I run mine at 880. This is because i am running unmatched cards, so one is a gigabyte and the other is a asus. Both are 1gb cards too.

As second 7870 would almost double your fps, pitcairn gpus scale very well. They are also HTPC dream card's because the second card shuts down when your not gaming, and the first card idles down and is silent, but when you want to game it delivers.
Compared with the pair of Vapor-x toxic HD-4870's they replaced. The pair of HD-7850's are quieter at full load...

need4speeds

Distinguished
I think it's the memory bus that goes from the gpu's memory controller to the memory. AMD did things to improve this with later gpus like the R370 and finally with HBM memory.

I found with my HD-7850's the clock speed only makes more noise. I run mine at 880. This is because i am running unmatched cards, so one is a gigabyte and the other is a asus. Both are 1gb cards too.

As second 7870 would almost double your fps, pitcairn gpus scale very well. They are also HTPC dream card's because the second card shuts down when your not gaming, and the first card idles down and is silent, but when you want to game it delivers.
Compared with the pair of Vapor-x toxic HD-4870's they replaced. The pair of HD-7850's are quieter at full load than the HD-4870's at idle and twice as fast. I am running a A6-3650@3.56ghz.

Back in the mining days, i found bumping the memory up helped one card, the other one crashes the memory just above stock.
I think 1360mhz was the sweet spot for the memory on the asus card, it's a 860mhz non-oc card but can run up to 1050mhz PT 10%.
The gigabyte is a factory OC card at 900mhz. It crashes at 890mhz. So i run both at 880 so they match. The gigabyte wont OC the memory either.
It has a nice cooler on it with 2 fans while the asus has a cheap cooler with one fan, but the asus OC's better so it's the gpu binning.
 
Solution

PanStef

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Apr 19, 2014
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4,660
Mine is a sapphire one, with 1000mhz stock core speed and 1200mhz memory speed. i did some testing and i saw that increasing the memory speed gave me extreme scores. So now all i got to do is do some stability testing and find and sweet spot.