Windows sometimes freezes after cold boot
About 50% of the time, when I turn on my PC after it's been off for a long time, Windows will freeze on me. The freeze doesn't happen during the post, it only happens in Windows 7. If I turn on my PC and then go to do something, I'll come back and screen is frozen on the login page. Or if I turn on my PC and then login and do stuff, it will freeze within 10 minutes. After I switch off the power supply and switch it back on and then power on, the system behaves great. I don't get any more freezes at all the rest of the day. So it seems this is a cold boot issue only.
Some other clues:
-This problem started happening after I moved my setup to a new case while at the same time installing a new video card (GTX 560). During the move I did also tighten the bolts which control the contact between the cpu heatsink and its backplate. I never removed the heatsink. I did twist the heatsink a little to test its contact with the CPU, it moved a little. I used Artic Silver 5 previously as the compound. I never got this freeze issue until this move a to new case/video card.
-I recently installed an SSD so I used that as an opportunity to do a fresh reinstall Windows 7. The problem didn't go away with the Windows 7 reinstall. So I don't think this is a driver issue.
-I have 4 x 4GB RAM installed, I ran memtest86+ all day and it passed.
-I've never had my system freeze during gaming. The GTX 560 also ran video card stress tests like Furmark with no problems.
Some things I'm considering trying:
-I have a spare video card, GeForce 210, which I'm tempted to swap in to isolate whether its the GTX 560 video card. This is a pain though since I won't be able to game.
-Remove CPU heatsink, clean off old compound and reapply new compound, reseat it. I'm not sure this will fix it as my CPU temps are normal.
Any other things I should try? Thanks.
Intel i5-750 stock
EVGA P55 LE 1156 mobo
4 x 4GB DDR3 (Corsair Vengeance 1600MHz, 9-9-9-24, 1.5V)
Asus GTX 560 1GB
XFX 650W PSU XXX Edition
Samsung 830 256GB SSD (Windows 7 Pro x64 installed)
Samsung 1TB SATA Drive