I have a x58 based rampage II extreme with an overclocked i7 920 (@3.6) with memory at 1600mhz

2x XFX 7970 @1.0V, 1000mhz core, 1500mhz memory

using cgminer with mostly default settings, mining LTCs , with thread-concurrency set to 22400 and nothing else

using catalyst 13.3 beta3 (same results as 12.8 and 12.10)

I can't get past 520kHash/s per GPU @ intensity 13

any other intensity and hashrate drops to ~200-300khash/s

overclocking the gpus even further gets a few extra khashes at the expense of more power consuption. this balance of power/noise and hashrate is the most efficient for me


my friend has as similar configuration, but with a Z77 based motherboard and a i7 3770k

he can get 620kHash/s per GPU @ intensity 18 (same GPUs, same clocks, same cgminer/drivers/windows version)

does the mobo/cpu combo has such effect on hashrate and acceptable intensity?
what is in fact intensity?
does PCI-e 3.0 makes a difference ?