I have the following PC:

Thermaltake 850W power supply (SP-850M)
ULTRA X-Blaster Black Chassis with EVGA X58 SLI Micro motherboard (121-BL-E756-TR)
Intel Core i7 Processor (i7-920)
XigmaTek CPU Cooler (HDT-SD964) with 1 additional XigmaTek Brushless DC Fan (AD0912HX-A7BHL)
NVidia GEForce 660Ti
WDBlack 1TB HDD (WD1002-FAEX) [main HDD]
WDCaviar Green 1TB HDD (WD-10EARS) [additional storage]
6 GB RAM
additional front and back ventilation fans

BIOS says that the CPU temperature is 31°/32°C.
I can't raise the base clock. (CPU Clock Ratio currently set to 20 X in BIOS)

I realize I possibly posted irrelevant information. lol But in case.

I recently read about overclocking my processor to get better performance. With this PC, how far can I safely push this processor? Are there any good instructional websites that can guide me through the process? Also, would you reccommend overclocking my GFX card?