Sabertooth P67 keep restarting

Hello,

I just make a new system:
Sabertooth P67
i7 2600K
G.Skill 2*4GB
GF GTX 570

I installed Windows 7 Pro 64 bit. Everything booted fine but after 5 minutes the system just crashed and restarted with no blue screen. I read somewhere it said this related to hardware, so what I've done so far are
- Update Bios to the newest version
- Enable PCI express option in advance bios setting
- Remove WD HDD and leave only my Intel SDD to boot
- Swap RAMs.
- Re-seat cpu

None of above solves the problem. My cpu at idle is ~44C so I don't think it could be a problem. I'm kinda hit the dead end right now. If you have any suggestion it would be very appreciated. Thank you !

44ºC at idle in Windows? That seems rather high. What's the room temp?

Assuming it's not temp-related, if it just happens randomly at idle then it points to a power supply problem.

Do you have both the 24-pin and 8-pin mainboard power connections used? What's the brand and model of your power supply?

Edit: Also, I assume you're still running at stock speed for now?

You put the RAM in the second and fourth slots like you're supposed to right?

Slot 1 (closest to CPU): Empty
Slot 2: RAM
Slot 3: Empty
Slot 4: RAM

And before you condemn G.Skill to the black list: Did you make sure the RAM timings in the BIOS were correct? Do you have other RAM to test? It could just as easily be a bad RAM slot or wrong timings.

If the Corsair worked, then try a Corsair Vengeance 8GB kit. I have heard that some ASUS boards don't like G.Skill RAM, but others have used it fine.