Friend's computer doesn't work right

He claims it works when it wants to pretty much. The thing is, sometimes it turns on, sometimes it doesn't. When it does turn on, sometimes it works fine for an hour or more, sometimes it turns on for 2-5 seconds and shuts off. He tried:

- Resetting BIOS
- Resetting PSU (by touching the pins on the plug-part of the PSU together)
- Removing unneeded hardware (HDD, optical drive, GPU)
- Stress testing (Prime95) (when he did get into Windows for a while)

- Any ideas? I would think PSU, but wouldn't the computer not turn on at all in that case?

- Then theres overheating, but that doesn't explain why the computer turns on for 2-5 seconds even on a cold boot, then can last an hour.

- Could be HDD, but I doubt that as well.

- Maybe CPU or RAM? But then again wouldn't a CPU issue stop the computer from booting at all, and RAM just cause BSoD's?
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  1. have you tried to take the parts out of the case yet? because you said it is overheating and the case might be causing that.
  2. Oh sorry, I meant that overheating probably is not a factor. He ran Prime95 for a good 15 mins and CPU temps were below 60C.

    Not that 15 mins is a real long period of time to check for overheating, but when cold booting his computer, I doubt that the CPU would even go near the point of overheating.
  3. I had a similar problem with my pc, i upgraded from an AMD athlonx2 to my C2Q;
    I reinstalled my windows, worked fine, then installed drivers etc, next morning didn't come on at all, went 2 school, came back and it worked again...

    swapped psu and my problems were history...
    try swapping psu, it helped for me
  4. Unfortunately, diagnosing and addressing this problem will be a tedious, time-consuming, methodical tasks. You cannot jump straight to Windows and play games if you want to diagnose this problem. Prime95 is by no means the best way to check RAM stability. I wrote this earlier today for a RAM diagnosis problem. Sorry if it only 90% applies to you.

    Step 1) What is the make and model of your PSU? If you're in Windows, install and run HWMonitor and tell me all the voltages it gives you (3.3V, 5V, +12V, -12V, CPU). If you're not in Windows, go to your Bios and look at the Hardware Status or Health menu and tell me what voltages it reads out. I doubt this is your problem, but always start at the PSU.

    Step 2) Install Memtest86+ to a flash stick. Power off your computer and disconnect your hard drive so you don't waste time accidentally booting Windows.

    Step 3) Since you think RAM is the problem... Remove all sticks except for 1 and cycle it through all the RAM slots on your board and see if it posts consistently with any of the slots. I had a motherboard where the first two slots had to be set slower than the other two. Repeat with all your other RAM sticks to determine if any configuration posts consistently. If not, then it's less likely that it's the RAM. (Do not connect your hard drive). Only connect 1 stick in whichever slot works best.

    Step 4) When you do get your computer to POST, go to your Bios and load defaults. Change your RAM to 1066MHz and 9-9-9-30 timings w/ 1.65V or whatever the RAM reads on it. Save and Exit and boot to your flash stick. Run through at least 1 cycle of Memtest86+, two would be better. Swap your RAM sticks and repeat Memtest86+. Put in all your RAM and repeat Memtest86+. If you pass two complete Memtest86+ run throughs without seeing any errors such as freezes or error messages (should take about 30 min per run through), your RAM is not the problem.

    Step 5) Does your computer consistently POST? With whichever RAM sticks and slots that work connected and set to 1066MHz 9-9-9-30 (Auto on all the rest), enter your bios. Check that your CPU speed and voltages are set to manufacturer defaults (Intel has a helpful webpage for every CPU). Connect your hard drive and boot Windows.

    Step 6) In Windows, start HWMonitor. Keep an eye on voltages because they shouldn't fluctuate much at all. Tell me your idle CPU temp. Now run LinX on a problem size of 10000 for 3 loops. Did it freeze, BSOD, crash, or return errors? Stop LinX if you exceed max temps specified by Intel (go with 70C for C2D, 80C for Nehalem). Did it freeze or crash? If your temps don't get too hot, run LinX for 20 loops and see if it gets errors. If not, then it's not your CPU or RAM.

    Step 7) Install MSI Afterburner with Kombustor or install Furmark. Run Kombustor/Furmark, monitoring your GPU temps. Do you get errors. If so, download new drivers and perform a custom "Clean Install". Check your device manager (after a restart) to see if there is any software lacking drivers. Attempt to describe your restarts. At this point (if nothing else was erring out, it's VERY likely that it's a bad PSU. Alternatively, it may be a bad mobo. RMA one of them.

    Please report any unusual errors or stumbling blocks in the above processes.
  5. This kind of issue is usually caused by a problem PSU. What brand and model (not just wattage) is it?
    Also, please provide complete specs on this system; either the model number and description if it's a prebuilt, or a list of parts if he (or a boutique shop) built it. What is the CPU and graphics card? Those will give the most indication of how much power it needs.
  6. Also check to make sure all of his RAM is seated properly
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