ive got a sapphire 6790. Im dont know much about overclocking so i just got some questions.
I have used MSI afterburner to clock my card. Its now clock: 890mhz *was 840mhz* memory: 1090mhz *was 1050mhz*.
The card is stable and going cooler *somehow* then when it was normal.
I did test with FurMark, Msi Combustor. It was 38c when idle now its 41c idle but underload it was 76c now 67c. It makes no sense.
Also would it be ok to keep the gpu like this for the however long the card lasts and also will the warranty void even if it wasnt overclockings fault?
What I would do is run a benchmark like 3DMark11 at stock speed, then once more with the overclock and make sure the GPU score increased, I would only do this to make sure your overclock is being applied as your temperatures are alittle strange.
Also I'd recommend only overclocking one part of the card at a time (Either the core or the memory) as it makes stability testing easier if your trying to work out what wasn't stable.
Well your 3DMark11 results tell us that your overclock is being applied and is increasing performance so I wouldn't worry about the strange temp difference you got before, just make sure you stay below 90C
With regards to warranty, almost all Venders state that overclocking will void your warranty but aslong as your only overclocking via software then they can't tell if you've overclocked.
Also provided you stay below 90C under load and don't go crazy with voltage adjustments (if you make any at all) then your card should be fine.
If you are playing with the card's voltage then make sure to check out what is a safe limit and what is dangerous.