Super User is a question and answer site for computer enthusiasts and power users. Join them; it only takes a minute:

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

I need help narrowing down the possible causes of a recent problem I have been having with my computer, due to a whole host of changes I made around the time of the problems appearance I don't know where to start.

Firstly the computer,

I built it around 2-3 years ago.

It has:

  • a 9800gtx+ gpu (replacement for one that died a year ago)
  • a corsair 620watt power supply
  • 2 hard drives both Samsung Spinpoints (one is as old as the computer, the other is new)
  • a gigabyte s-series motherboard
  • an intel core 2 quad cpu
  • 4 gb (two 2gb ram sticks) of kingston ddr2 ram
  • dual booting windows xp (since construction) and alongside windows 7 (recent), it was windows xp and ubuntu until a few months ago

Strange occurrences before the problem:

  • Around a year ago the originally 8800gts 512 gpu died after 2 years of service replace with current card.

  • Current 9800gtx+ ran perfectly up until around 2 months ago when the monitor would randomly lose connection to the monitor similar to current situation when playing certain games forcing a hard reset of the computer. I rolled back the drivers and the problem hasn't happened since but I have not actively attempted to recreate the problem so it may be the issue. This was on the windows xp partition, I have not had the error occur on windows 7

What I have done to the computer recently

  • Recently removed ubuntu and the grub mbr, replacing it with windows 7 using the default windows boot manager
  • Installed a new hardrive, the hardrive features no essential programs or parts of the operating system on it, only a few games

Detailed description of the problem

Sometimes when I turn on the computer, the monitor remains blank. Neither the gpu bios screen or the mobo bios screen appear. My keyboard's (ps/2) num lock key lights up. It would appear windows continues to boot in the background as when I am inevitably forced to reset my computer and it starts normally, windows 7 complains about being shut down incorrectly.

The fact that the problem manifests itself before any boot screen suggests that the new windows installation can be ruled out as the culprit or am I wrong?

So there we are, hopefully you guys can help me narrow down what area I should start looking into first as I am at a loss where to begin.

share|improve this question

If your numlock lights up, computer doesn't produce (error) beep codes, and your hard drive light blinks or stays on during the boot process, then your computer seems to be booting just fine but doesn't seem to be able to wake up the monitor.

Here are the possibilities in order from what I consider to be most likely to least likely:

The monitor could be flaking out. Next time it happens, turn your monitor off and on again or try a different one if you have a spare.

Your video card could also be flaking out. If there is a lot of dust on the video card or if the video card fan is broken, it could have heat damage.

The video cable might be knocked loose or have a bad connection.

The only way I know how to determine which one it is, is by swapping parts (guess and check).

Good luck.

share|improve this answer
edit:However, Once the num lock lights up, when I press the num lock key again it just stays lit same with all other keys. The computer starts up no problem afterwards with no alteration to the cable so it can't be a poor connection or damaged cable since the cable doesn't move. The gfx card has already shown similar symptoms before so it would be most likely that I think. The problem with switching out parts is this happens only maybe once every 10 boots so its very difficult to replicate. Also once the computer does correctly boot it runs fine even in games such as The Witcher 2. – DevTim Oct 2 '11 at 23:25
Ok, that does make it sound a lot less like a monitor issue and a bit more like a video card or motherboard issue. I've had the same problem with my computer except the hard drive light stays off and it does not warn me about an improper shutdown upon reboot. For me it only happens when I first try starting up. I think mine is a motherboard issue since I tried replacing the video card. Your issue sounds a bit different since it sounds like it is able to boot but not activate the screen. – James T Oct 2 '11 at 23:40
Yeah, I can live with it but of course I am in perpetual fear of one day the thing not turning on at all. Btw correction on earlier point, it turns out the keyboard was unresponsive as in the background it was in the windows boot. When I booting normally the same issue occurred during the Starting Windows page. Anyway my gpu should be covered by the standard EU warranty (Although it was a replacement for my other card through warranty). Hmm, it probably is the gpu but I find it odd that it would die after only 8 months. It's got adequate power, it's not overclocked and it's cool. Puzzling. – DevTim Oct 2 '11 at 23:53
there are tests that you can put the GPU through very hard work, harder work than most games, and see if it fails. Like furmark, for the gpu chip, and something else to stress the video memory. If the gpu card has a flaw or not enough cooling, these tests will lockup. the idea being to isolate the work to a specific item, and test it. – Psycogeek Oct 3 '11 at 2:00
good advice Psycogeek and I just remembered the gfx card came with a full license to FutureMark that I never used. Once I get a chance, I'll run it and see if it kills my gpu. If it does I need to figure out why my gpu's are dying. The first one I believe died due to insufficient power but this one has a each of it's 2 power connectors on a different rail. – DevTim Oct 3 '11 at 18:57

You must log in to answer this question.

protected by bwDraco Mar 20 '15 at 22:03

Thank you for your interest in this question. Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).

Would you like to answer one of these unanswered questions instead?

Not the answer you're looking for? Browse other questions tagged .