I also noticed skein doesnt need high memory frequency so you can decrease it almost all the way down without any performance hit. Skein miner is probably not optimized yet and thats why it needs less power i guess.
The kernel does not use VRAM at all (save for tiny bit to pass back results to miner), so yes, you can downclock it to minimum. It is optimized, though, but for GCN. Chances are that if you replace rolhack functions with rotates, arrays with variables and unroll skein rounds, it will perform better on VLIW architectures.
To confirm the facts above:
Running at 300Mhz memory frequency, same speed as 700 or 1200Mhz on a AMD 7970.
(Same as any SHA256 coin).
Others have measures >100W power savings at 300MHz compared to 1500MHz. Anyone care to confirm?
Miner is running about 3x slower than cgminer on bitcoin, on my 32 bit Python installation.
Any idea if a 64bit Python compile will boost the hashrate? (As skein is supposed to be faster at 64bit)
Tested -w 256/128 and -f 1/5/10/30 with no major speed gains on an AMD 7970.
sleinhash.so is only used in other threads than the one that runs the kernel (does actual solutions search), so no, 64bit will not yield more performance. Skeinhash functions can even be rewritten in pure Python without losing any performance.