Computer turns on for a few seconds then turns off before BIOS

Hello there,
So my computer has been having this recurring problem. I don't know when it started but it's happened so frequently that its driving me nuts. So MOST times, when I start my computer, the computer turns on, the fans start up, and then the computer turns off before BIOS. Sometimes I'll press the power button 20+ times until the computer gets to BIOS and everything works just fine.

Here are some specs for my computer [Btw where do you guys go to find the full specs on your computer that you guys post for everyone to see?]

Windows (Service Pack 3)
Intel® Core™2 Quad CPU Q6600 @ 2.40GHz
2.42 GHz
3.25 GB [4x Crucial]
AMD Radeon HD 7800 Series
700W Thermaltake Toughpower


1)So at first, I thought I needed to repaste the thermal paste because my computer is 5+ years old. So I took off the heatsink, used 99% iso-alcohol, and put on Arctic Silver 5. I turned on the computer after that and it worked on the first try. Just to check again, I turned it off and tried to turn it back on. The same problem persisted after several attempts.

2) I read that it was possibly an electrical short. So I took everything apart. Motherboard, PSU, HDD, everything was outside the case. I just plugged in the barebones for my testing. So the main components, HDD, PSU, Graphics. Everything turned on just fine. 10/10 attempts. Then I plugged in all the peripherals, (CD, Audio cards, case fans, floppy/microSD reader) and tested the computer to turn on before plugging in a new component. The problem occured again when I plugged the power into the floppy/microSD drive with that cable connected to case fans. So I gave that floppy/microSD drive its own cable, and everything worked 5/5 attempts after that. So I plugged everything back into the case the exact same way I had it. Tried to turn on the computer and the problem persisted again. OH THE FRUSTRATION!

3) I took everything apart again and used barebones. Once again 10/10. This time, I put the components into the case 1 at a time and tested 5x. Motherboard with barebones worked 5/5. Inside the case, the problem occured again when I added an audio card. So I removed the audio card and the problem would still persist! So it wasn't JUST the audio card.

4) After the audio card, I suspected the GPU or its power consumption. My GPU was connected to my big screen 40" tv through HDMI. I tried disconnecting the HDMI cable and turned on the computer. I listened for the POST beep, which happens when it successfully goes through BIOS. Sometimes it would work, but after while it didnt work and continued to shut off. Just checked now and 0/5 attempts.

5) So my next test is removing the power cable from the GPU. I know BIOS doesn't go all the way through because it doesn't detect a GPU, but the fans continued to stay on and doesnt shut off 5/5 attempts.

So I'm guessing it has to do with the power for the GPU? But as I stated in the 2nd test. Everything worked just fine outside of the case. BIOS appeared on-screen with GPU plugged in 10/10.

So I come to you experts. I apologize if this was TLDR, but I wanted to give you as much detail as possible, just so you don't have to suggest "well did you try this or that?"

I don't think the RAM has any problems. I didn't touch it during my tests. I was able to turn on the computer with all 4 sticks in so I disregarded it. I thank all of you who read and come up with suggestions.
4 answers Last reply Best Answer
More about computer turns seconds turns bios
  1. Best answer
    Try disconnecting the floppy/microSD and any other nonessential USB devices also reseat the memory, just take it outand reinstall it.
  2. hey! whatta ya know! so far its worked 5/5 attempts. Now I'm going to reconnect everything 1 by 1 and see if everything will work. I'll update afterwards
  3. EVERYTHING WORKS!!! I've searched dozens of forums on this particular problem & memory was the last thing I was gonna do. Actually I was so fed up, I probably would've skipped it. I had Newegg tabs open and a PSU in my cart ready to be purchased. You saved me a ton. I can't thank you enough knightdog56
  4. Best answer selected by Sparkiekun.
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