Race Driver GRID freezes

Specs
Processor: Intel Core 2 Duo E8400
Motherboard: Asus P5Q-E (BIOS 1003)
Graphics Card: ATI Radeon HD 4850
RAM: OCZ SLI-Ready nVidia DDR2 PC8500

I managed to overclock my E8400 processor to 4 Ghz, and it took 2hr to become very stable, and now I have no problem on the desktop. But when I run Race Driver GRID, I have a freeze at the beginning of a race. So I have to reboot, and this happens routinely. I also had freezes or reboot with bluescreen on other games (FSX, Crysis). As against, when I withdrew the OC, I have no problem.

BIOS settings
CPU ratio: 8
CPU Vcore: 1.39 V
Intel virtualization tech: Disabled
Intel C1E: Disabled
FSB frequency: 500 MHz
DRAM Frequency: 1000 MHz
DRAM Timings: 5-5-5-15
Mem OC Charger: Disabled
MEM training read: Disabled
DRAM voltage: 2.1 V
CPU PLL voltage: 1.56 V
FSB Voltage: 1.39 V
NB Voltage: 1.39 V
SB Voltage: 1.3 V

Temperature: 40/40 and 64/65 in idle in full.

Everything should be standard, my PC is stable, yet my PC freeze or reboot in games.

Need advise.

You did not changed the frequency PCIE (100 by default)?

Must do tests to see where the problem comes, for example you de-sync your memory, put the 1000mhz frequency from below and retest your games to see if you have blue screen.

You FSB Strap in bios on the motherboard? If so put it in 333MHz.

My PCIE Frequency is 100 MHz. I lowered FSB to 444 MHz for a ration of 9. So I turn to 3994 MHz with the same vcore. I never had a freeze?