Random restarts or freezes? DISABLE C-STATES IN BIOS!!!

Question

I would like to offer my advise to any of you experiencing random restarts or freezes with their rig.
I’ve recently got myself a new rig (RAM and graphics are from my old rig):
Corsair VS550 PSU (550W)
MSI Z77A-GA43 motherboard
i5-3470 CPU
4 x 4 GB Corsair 1333 Value RAM
MSI 6850 Cyclone VGA
After first assembly and fresh system install I’ve started experiencing random restarts, but ONLY when the computer was idle or under light load, like WWW browsing or writing in Word – it never happened in games or Prime95. Sometimes the restarts would occur every hour, sometimes every couple of days. Suddenly the screen would simply turn black, then there was a pause of 2-3 seconds, and then the system would start normally with the usual "Windows was not closed correctly" screen.
This drove me crazy. Since I still had my old rig available (and a few spare parts, like an older VGA and RAM), I was able to exchange every component (PSU, motherboard, CPU, RAM and VGA) to rule out any hardware problems, but the problem would persist except when I switched the motherboard – then it was fine, no restarts. So the culprit was undoubtedly the new motherboard.
Then I started looking for other users on the net with a similar problem and found a very large number of such postings, one of which brought the solution!
It turns out that the problem is not restricted to any particular motherboard model or even brand, but is more universal. Damn you Microsoft! They wrongly implemented the C-STATES support in their Windows 7 and 8 OS. So when the CPU lowers its clock or parts of it are sent to sleep when in idle or under light load, under some unknown conditions (not all users have this problem obviously) Windows wrongly interprets such a state, and as a result a reset of freeze occurs. In my old motherboard, C-STATES were turned off by default, so I've never experienced that problem before.
So the solution is very simple: turn off all C-STATES in BIOS (in Z77A-GA43, they are under Overclocking -> CPU features -> C1E Support & Intel C-State), but leave EIST (Enhanced Intel Speedstep Technology) on so that the CPU can downclock to 1600 MHz and lower its voltage during light load.
The result: the problem immediately disappeared and hasn’t occurred again for weeks now. For testing purposes, I switched the C-STATES on again and the computer restarted itself after 1,5h in idle. Bingo!
So thanks Microsoft for your wonderful operating system!     
Maybe MSI could consider switching C-STATES off in BIOS by default until Microsoft comes up with a fix? Wouldn't that reduce user frustration and the number of unnecessary RMAs?

Answer 1

You can probably enable C1E and not have the problem return. All my boards have C-State disabled. EIST and C1E seem to work well together.