Ohk, so I got a new GTX 660 from EVGA and I think I've got a good card. At stock voltage I managed to overclock it to 1256MHz on the GPU core. Can other people post their overclocking results on their gtx 660's so I can compare?
I have a 660ti @1200 but that is a gk104 and I am not sure how they compare to the gk106 in overclocking
I have a 2 GTX 660s from ASUS both run about the same both run at 1215 full time stable one can go higher than the other. however on mine you can only set the minimum voltage and I would need to flash a new bios to go any further. I did get them both up around 1270 - 1300 for a bench run once but they weren't stable for 24/7 use.
I run my Galaxy GC card at 1325 with custom BIOS. There is a great forum out there for specific gtx 660 overclocking. I'll link it when i find it.
Link to forum: http://www.overclock.net/t/1330897/official-gtx-660-non-ti-owners-club