Asus Gtx660ti Overclocking Help

Hey,

I am having some weird issues with games when my GPU is OCed the core clock doesnt reach anything above the stock core clock speed of 915Mhz, ie it stays around 732Mhz but when I force a constant voltage it goes up to 915Mhz but still it doesnt go any higher than that.

Gfx Card = Asus GTX 660 TI-DC2-2GD5
My current OC is

Core Voltage = +0
Power Limit = +123%
Core Clock = +40Mhz
Memory Clock = +300Mhz

Any help would be great

Haev you overvolted it with the 40 Mhz OC.? Dropping back to 732 sounds like throttling to me, are your temps OK? Whar OS are you using' I was having issues using AB with Win8.
Are you monitoring it under load? Cards dial back to save power if not being stressed!

+1 to Johan, also what are you using to verify the clock speeds?