New Built Computer Does not turn on

By johnt2008 ยท 31 replies
Jan 5, 2006
  1. Hello, I just built my new computer but when i hit the power button, the power light flashes for 1 second and my processor fan and case fan spins for about 2 seconds but the computer will not start. I think have everything plugged in.

    Comp Spec:
    AMD XP 64 3700+
    GEFORCE 7800 GT
    ASUS A8N5X

    Please help!
  2. zachig

    zachig TS Rookie Posts: 23

    I'm almost 100% sure that it's your PSU that's causing the problem!!!
    the PSU that you currently have is considered as a generic one and is also VERY LOW in Wattage. I'm pretty sure that it is 400W 'Peak-Power' and not 'True-Power'. If you'll read the recommendations for a 7800GT, you'll see that you need a PSU of at least 430W-450W (of a decent PSU).

    My suggestion, first of all, replace your PSU. Go and buy yourself a decent PSU with sufficient Wattage like: OCZ PowerStream (or ModStream) 520W, PC Power&Cooling 500W, Enermax 535W, etc.


    If you have more questions, don't hesitate to ask! :wave:
  3. Bender99

    Bender99 TS Rookie Posts: 21

    Probably the ps like zach said. The newer video cards require a lot of juice.
  4. mailpup

    mailpup TS Special Forces Posts: 7,155   +458

    Besides the power from the motherboard slot, your graphics card needs a separate power supply connection. Is that connected? Also, is the small 2x2 white connector on the motherboard connected to the power supply? That is sometimes overlooked.
  5. Jaquio

    Jaquio TS Rookie Posts: 26

    Yeah... i just have the same problem and it was the PSU... so... make sure you test it on another system to see if it does the same thing... and go ahead and buy a new one...
    500W+ Rulz!!!
  6. johnt2008

    johnt2008 TS Rookie Topic Starter

    Thanks for the reply, I have the 2x2 white connector connected but what is the power supply connection to the video card?

    Also I took out my video card and tried to turn the computer on and the same thing happened so could this be another issue?
  7. iss

    iss TechSpot Chancellor Posts: 1,994

    Codegen PSU's are absoute garbage. the first P4 system I built had a 300 watt codegen PSU in it andit did just the same as you are describing. I checked the ratings and the 300 watt PSU was only delivering 10A on the 12V rail. I put an antec 330 watt PSU in and it booted up fine.

    the 7800Gt card has a connection on it that requires a 4 pin molex power lead fromt he PSU be connected to it.
  8. johnt2008

    johnt2008 TS Rookie Topic Starter

    I found the connection from the card to the PSU, but it was never connected so could it be the PSU doesn't have enough power to even turn everything else on?
  9. formetopoopon90

    formetopoopon90 TS Rookie

    Hello. I would like to say i had the EXACT same problem, and i know how you feel :eek: . I thought it was my PSU too but it turned out to be my thermalpaste. Well, i didn't have any on. It didn't really seem to be all that big of a deal to me but it was. I bought about 200-300 worth of new computer parts, and it didn't work. I went to the computer store, bought a cheep heatsink fan and thermalpaste and it worked like a charm. Amazing how the small things can really add up :unch:

    Good luck, and keep posting on your progress. :chef:
  10. mailpup

    mailpup TS Special Forces Posts: 7,155   +458

    Your PC won't turn on without the graphics card installed and unless the extra power connector is connected to the power supply, the graphics card won't work. Connect it and your problem should be solved.
  11. Jaquio

    Jaquio TS Rookie Posts: 26

    Just hook the molex to the vid card... and see what happens...
  12. kirock

    kirock TS Rookie Posts: 1,221

    Plug the molex connector into the video card. If it still doesn't boot then you have 1 of 2 problems or both.
    1) under powered PSU
    2) overheating CPU due to faulty heatsink/fan and thermal paste installation.
    3) both 1 and 2.
  13. johnt2008

    johnt2008 TS Rookie Topic Starter

    I don't think that the CPU is faulty due to heatsink/fan and thermal paste because It is brand new. I think it might be not enough power on the current power supply i'm using. Thanks for the replies guys I will go buy a new power supply and test it out to see if it works.
  14. mailpup

    mailpup TS Special Forces Posts: 7,155   +458

    Your psu may or may not have enough power but I don't understand your reluctance to simply plug in your graphics card. Regardless of how good your power supply is, your graphics card won't work unless you plug in the additional power connector and your system won't turn on if your graphics card is not working. That extra power connector is not an optional thing that you can just disregard. Or did I misunderstand you?
  15. johnt2008

    johnt2008 TS Rookie Topic Starter

    I have already plugged the power connector to the video card... I was just wondering If it could have been another issue because even without the video card the computer will not turn on. I thought that the computer can turn on without the video card.
  16. blue_dragon

    blue_dragon TS Rookie Posts: 190

    just be careful with that video card and lame psu
    your psu can send your video card and other components to computer heaven earlier than you think!! :angel:
  17. mailpup

    mailpup TS Special Forces Posts: 7,155   +458

    Okay. I gotcha.
  18. kodrutz

    kodrutz TS Booster Posts: 110

    You could try a different video card, one with lower power requirements, something like a x300, 6200 or so, to see if it boots up. Try to check all the possible jumpers if any, also you can try and clear the BIOS, and try to boot without hdd or any optical drives.
  19. johnt2008

    johnt2008 TS Rookie Topic Starter

    I just got a brand new PSU today. It is a Enermex 535 as suggested but I still have the same problem. The only difference is the fan spins a few seconds longer and the PSU light stays on longer but the computer will not turn on. Anybody have any other suggestions plese?
  20. kirock

    kirock TS Rookie Posts: 1,221

    Well here's the part where ppl were trying to suggest that the installation (not the actual CPU or Fan/heatsink itself) of the fan/heatsink to the CPU may be at fault. Remove the assembly from the CPU and ensure you have adequate thermal compound AND that the heatsink sits flush to the CPU top surface. There should be no gap at all between the CPU and the heatsink.

    The whole point is, if this is not correct your CPU will instantly overheat and immediately shut down! Your symptoms are very similar, therefore we have asked/suggested you to check this.

    Another common problem with new builds is the mobo stand-offs. Make sure you have those installed correctly (the little insulating disks in place) and that the mobo is not grounding itself on any part of the case.

    Hope this helps.
  21. johnt2008

    johnt2008 TS Rookie Topic Starter

    Thanks it works now! The motherboard was too close to the case. My monitor wouldn't turn on so i tried to switch from 115V to 230V on the back of the PSU (DUMB MOVE)then suddenly I swear something burnt and now the computer wont turn on anymore! I think its the PSU because i switched back to my old PSU and everything turned on. I will post this on a different thread. Oh no, what have I done?...
  22. kirock

    kirock TS Rookie Posts: 1,221

    Johnt, please just keep posting on this thread so the process is easily followed by others and the solution can be tracked too.

    Sorry but I'm a little confused with your last post. When you saw the monitor not work, you changed the V switch on the PSU from 115 to 230V, then something burned (yes! a coil in the transformer inside the PSU). Was this before or after you corrected the mobo touching the case? That's my confusion: Just where do we stand now? The PC IS working with the old PSU (now that the mobo is clear of case) ? Good news!!! :)

    Your new PSU may not be though dead now though with any luck!
    Is this the Enermex 535???? Man I hope not. Did you try to put the V switch bk to 115V? The burning smell is a coil on the input side of the main transformer ( but each coil is wound seperately), so by moving the switch back to 115V you activate the 115V coil and maybe she'll fire up! (fire is a bad word) If it won't I'd try to warranty replace it (don't mention the switch thing)

  23. johnt2008

    johnt2008 TS Rookie Topic Starter

    I switched the V switch after the mobo was not touching the case. Then i smelled something burnt. So if I wanted replace the PSU, do I go back to the store and ask to be replaced, or ask to return?
  24. johnt2008

    johnt2008 TS Rookie Topic Starter

    I switched the V switch after the mobo was not touching the case and yes, this is an Emermax 535W. Then i smelled something burnt. I also tried switching the V switch back in forth but will still not turn on. So if I wanted replace the PSU, do I go back to the store and ask to be replaced, or ask to return?

    There also seems to be another issue with my monitor because the power light is on but there is no display on the monitor.
  25. zachig

    zachig TS Rookie Posts: 23


    I'm sorry to tell you this, but you BLEW OFF you PSU. Hopefully there is a FUSE inside your PSU that can be replaced. You can replace it (or a technician) but ONLY IF YOU REALLY KNOW WHAT YOU'RE DOING. If not, you should go and buy a NEW PSU.

    You can also try to RMA it. Just tell the store that you bought it from, that it just BLOW OFF without any reason. :haha:
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