Ah... mine hasn't done that yet. I think you can use flags to turn it down and maybe not use all your GPU?Yes mine is around there too and actually crashing my PC =\.
That sounds like a plan, mine's only at 40% fan speed with 100% activity...Change your fan speeds...
What pool and program are you using out of interest?Yeah it puts a lot of stress on your GPU. I keep my fan speed at 50%, hovers around 68-70C.
GUI Miner. I'm using the reddit pool at https://mtred.com/What pool and program are you using out of interest?
I just put my fan to 50% and that's only got it to around 80C, sounds like either you have better case cooling or 6970s run cooler (or a bit of both )
It's something to do with the AMD architecture being more efficient for the tasks BTC mining has.What exactly is different that makes the ATI cards so much better at this than nvidia? I see the lowest 6990 on that list is doing about 670MH/s whereas the GTX 580/590 seem to do 150-190. I know the 6990 is a better card but the 580 is better than mine for gaming and everything else, what determines that I get about twice the performance in this as that card?
It is down to significant architectural differences, basically more (but less complex) shaders give AMD the advantage. From the Bitcoin wiki:What exactly is different that makes the ATI cards so much better at this than nvidia? I see the lowest 6990 on that list is doing about 670MH/s whereas the GTX 580/590 seem to do 150-190. I know the 6990 is a better card but the 580 is better than mine for gaming and everything else, what determines that I get about twice the performance in this as that card?
Firstly, AMD designs GPUs with many simple ALUs/shaders (VLIW design) that run at a relatively low frequency clock (typically 1120-3200 ALUs at 625-900 MHz), whereas Nvidia's microarchitecture consists of fewer more complex ALUs and tries to compensate with a higher shader clock (typically 448-1024 ALUs at 1150-1544 MHz). Because of this VLIW vs. non-VLIW difference, Nvidia uses up more square millimeters of die space per ALU, hence can pack fewer of them per chip, and they hit the frequency wall sooner than AMD which prevents them from increasing the clock high enough to match or surpass AMD's performance. This translates to a raw ALU performance advantage for AMD:
AMD Radeon HD 6990: 3072 ALUs x 830 MHz = 2550 billion 32-bit instruction per second
Nvidia GTX 590: 1024 ALUs x 1214 MHz = 1243 billion 32-bit instruction per second
This approximate 2x-3x performance difference exists across the entire range of AMD and Nvidia GPUs. It is noticeably visible in all ALU-bound GPGPU workloads such as Bitcoin, password bruteforcers, etc.
Secondly, another difference favoring Bitcoin mining on AMD GPUs instead of Nvidia's is that the mining algorithm is based on SHA-256, which makes heavy use of the 32-bit integer right rotate operation. This operation can be implemented as a single hardware instruction on AMD GPUs, but requires three separate hardware instructions to be emulated on Nvidia GPUs (2 shifts + 1 add). This alone gives AMD another 1.7x performance advantage (~1900 instructions instead of ~3250 to execute the SHA-256 compression function).