Tuesday, 29 October 2013

Fiddling with GPU voltage - what does it do?

If you're like me, you'll never be happy with buying a CPU or GPU and leaving it alone. It's the same reason why people spend heaps of cash on extra cooling, the pursuit of more performance by pushing a component to make it faster than it was when you got it.

This is overclocking. 

So, what is overclocking to me? To me, it's more of a thrill than a necessity. At the moment, I can play all the games I want just fine at stock clocks, but I have an innate yearning to push the components further, because I want to. It's that simple. Overclocking is a little like chocolate. You don't need it, you want it.

So, as you might be able to tell from the title of this post, I'll be doing a quick exploration into what effects tweaking the voltage has on certain aspects of the GPU.


Testing Methodology

So, what's going to be happening? 
Basically, I'm going to be using my Asus HD7970 DirectCU II GPU in this test. It's a card I've grown to love and it has one of the best cooling units on any retail card available. I'm going to test it on two different voltages, 1.100v and 1.150v. I'll be keeping the clocks at 1000 MHz on the core and 5600 MHz on the memory, and measuring FPS and Temperatures on both cards after 10 minutes on FurMark (99% GPU Load).

So, lets get started!


Tests

TEST 1:

Specifications
Core: 1000 MHz
Memory: 5600 MHz
Chosen Voltage: 1.100 V (Actual monitored reading was 1.042 V)
Fan Speed: 25%

Temperatures
Start Temp: 30 C
End Temp: 77 C

Performance
Lowest FPS: 61
Average FPS: 62
Highest FPS: 76


TEST 2:

Specifications
Core: 1000 MHz
Memory: 5600 MHz
Chosen Voltage: 1.150 V (Actual monitored reading was 1.089 V)
Fan Speed: 25%

Temperatures
Start Temp: 30 C
End Temp: 82 C

Performance
Lowest FPS: 60
Average FPS: 62
Highest FPS: 76


Conclusion

I hope that those results have made clear my findings. That's a 5C difference with the same clocks, fan speed and room temperature. That's not something to dismiss, as 5C is actually quite a sizable difference, as one could easily achieve a higher clock rate at the same temperatures with a lowering of voltage.

What must be remembered though is the possible drawbacks of having your voltage set too low - instability can become a major problem with the voltage being set too low. Just remember, while overclocking is fun and useful, always be cautious, and know when you've gone far enough.

I'd just like to give a special thanks to the guys at the 79xx owners page at overclock.net, they were a great help during my testing.


Best Regards
Luke 

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