Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

What can be the reason for system freezes that are so "hard" that even the hardware reset button takes about 3 seconds until it actually resets the system (and then it actually powers down and up again instead of doing a "clean" hard reset like when pressing it during a normally running system).

Since it initially happened mainly while playing videos from YouTube I suspected the graphics card - however, I replaced it recently and it did not change it. It still happens from time to time (and sometimes more often, like a few times times in the last few hours).

The system is running Windows 7 - but I don't think this matters since I don't think any software, not even the OS, can actually affect the reset button's behaviour.

The PC is not overheated and the freezes happen randomly. There is also no malware on the system. The CPU is an Intel Core i7-920 on a Gigabyte EX58-UD5 mainboard.

What could be the cause for this problem? Faulty RAM? I did not run a full memtest86 check yet, but I wonder if there is a more likely issue than faulty RAM - checking 12G of ram does take some time after all!

There are no entries in the event log - but that's what I expected since the system freezes so hard that I doubt it has time to write anything to any log.

share|improve this question
It's dead to interrupts, so you have to force power off (which is what happens if you hold the power key in for several seconds). Ie, something has trashed the central core of the OS. – Daniel R Hicks Sep 27 '12 at 12:07
Well, the reset key does work - with a few-second delay. Not reacting to interrupts sounds plausible though; the power-cycle-style reset that happens after the delay could indeed by some watchdog detecting that the system is not rebooting... – ThiefMaster Sep 27 '12 at 12:15
No, there is hardware logic in the power supply that detects when the button is held in for a period of time and kills power. No software is involved. – Daniel R Hicks Sep 27 '12 at 12:27
Another possibility is that your power supply is marginal. This can cause hardware within the system, graphics adapters are particularly vulnerable, to hang or enter into strange states because they need just a little bit more power than the power supply is delivering. With video, stressing the adapter causes it to need more power. You may want to try swapping the power supply out with a known good one to see if that resolves it. – Yedric Sep 27 '12 at 12:29
To clarify, I do not have to hold the reset button pressed. I just press it once and then release it immediately. Regarding the power issue: There are no problems while playing HD videos (using VLC) or games with full details on 1920x1200 resolution. – ThiefMaster Sep 27 '12 at 12:31

What can be the reason for system freezes that are so "hard" that even the hardware reset button takes about 3 seconds until it actually resets the system

This distinction is not attributable to the "hardness" of a "freeze" of the operating system. This distinction also applies if your operating system is happily operating normally (try it now!).

The so-called "power" button is not a real power switch, it has two functions

  1. Signal the operating system that the user wishes the OS to change to a low-power state from a high-power state or vice versa. The low-power state might be configured to be any of power-off, hibernate, sleep or others.

  2. After being held for several seconds a separate hardware function is activated that signals the internal PSU to drop power to the CPU. This function does not require operating system assistance. This function can be triggerred even if the operating system is operating normally.

Historical note: The first IBM PC had a true power switch (the "Big Red Switch" or BRS) which simply cut the 120/240V power to the PSU. Inappropriate use of this caused data corruption for many people

Correction: The above was based on a mistaken assumption that the OP meant the "power" button whereas the OP really did mean a separate "reset" button which is provided for on most x86 motherboards.

What could be the cause for this problem?

Buggy video-card drivers can cause operating system lockup in those operating systems that provide privileged execution for video drivers for performance reasons. If a bug in the video driver causes the video-driver to become inoperative, it can be unobvious whether the OS is continuing to operate normally in all other regards.

share|improve this answer
I'm talking about the reset button, not the power button (they go to different connectors on the mainboard). So the first part of your answer is not really applicable.... – ThiefMaster Sep 27 '12 at 14:32
@Thiefmaster: None of my PCs or Servers have separate power and reset buttons, they all have a single button marked with the IEC 5009 standby symbol. – RedGrittyBrick Sep 27 '12 at 14:41
That's odd. Every case I bought had separate switches and every mainboard had separate connectors. The buttons also behave quite differently - the power button tells the OS to shutdown and pressing it for a few secs powers the system off without waiting for the OS. The reset button performs a reset without letting the OS perform a clean shutdown. – ThiefMaster Sep 27 '12 at 16:09

A CPU (and any integrated circuit with a reset pin) should always react to its reset signal.

Possible causes:

  • Reset signal is not reaching CPU. Not sure how the reset button pins are routed on your board but it may be that it actually goes to the chipset, and perhaps the chipset is buggy or faulty.

  • CPU is actually resetting but not getting very far in its BIOS due to an error very early in its initialization. A faulty CPU that fails its initial BIST (built-in self test), a failing BIOS flash chip, or a fault in the motherboard hardware (usually chipset) that routes interrupt signals.

  • Some thermal protection either on the CPU or chipset is misbehaving. Perhaps your fans are not correctly or completely connected or there is an issue there.

  • Power supply fault.

Very strange. All I can think of, really.

share|improve this answer

(generic answer)

I'm not sure, but the RESET button does not reload the BIOS bootstrap code into RAM, it just jumps to it. So if it has been changed by a defective driver, the RESET button dies. It was with that suspicion that I actually started a few searches, the last one being "pc freeze reset button not working"

A defective driver or a custom kernel might be able to replace that since it doesn't overwrite actual BIOS code. The power-down (4 seconds power button) makes the next boot load the initial program from the CMOS, thus "reloading the BIOS". That's why THAT works.

I have seen in a text-mode Linux kernel that whenever I pressed the Reset button there was an entire frame of new text (dunno, 10, 15 new lines triggered by the reset?) before actually resetting. One may note that RESET might not go to the actual BIOS location triggered by the normal boot...

You may look up the specifications for the Intel CPU... On Wikipedia the IBM PC does not clear RAM nor does it do the IPL, and that might have been inherited by our usual PCs, but I can't be sure until I actually experiment with it (maybe some code that indeed hooks the reset button?)

Any problems with this button thus might be software-related, though I can't know for sure (If the OS detects something like that from a driver it most likely BSODs, maybe since the respective pages might not be directly available and the driver is "caught" modifying the page table) But Linux has likely "been there, done that"...

Random stuff: The reset button on my PC is something like 4-5 inches away from the power button, and smaller and somewhat more difficult to press, though not impossible.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.