Computer will not turn on

By nimbus_racing · 58 replies
Mar 4, 2008
  1. kerz

    kerz TS Rookie Posts: 20

    Ok a few things I need to know.

    1) The adapter came with your monitor yes\no. If yes then it might not be the right type. I believe there are three types of DVI. It may look like its fits but may not be right for your card. Have you tried both heads on the card (video to monitor hook-up) ?

    2) The MOBO you said is a P4P800? if this is true all the P800 Asus boards only support AGP cards

    3) Take the card down to a local shop and have them plug it in to a lab PC and see if it works for them.
  2. nimbus_racing

    nimbus_racing TS Rookie Topic Starter Posts: 29

    1) the adapter came with the monitor. It was never running through DVI before anyway so I can't see how that's a problem although I have tried running it through dvi with the adapter.

    2) the p4p800 was the one that had the fried PSU. this is the computer that had the PSU that I took out to test the p4p800. this mobo is a msi 945pl neo.

    3) looks like i'll have to get around to it.
  3. kimsland

    kimsland Ex-TechSpotter Posts: 14,523

    Just to throw a spanner in the works, It is possible that it is the new Power Supply causing the issue.
  4. nimbus_racing

    nimbus_racing TS Rookie Topic Starter Posts: 29

    i think i need to clarify this lol!

    computer A: the original source of my problems (i.e. computer would not boot because PSU was fried)

    computer B: originally working computer that I borrowed PSU from to test computer A with. Now cannot receive picture

    So I took PSU from B and put it into A. That worked so I figured the PSU originally in A was fried. Got a brand new PSU and threw it into A, computer A now works fine. Put the PSU from B back into B after testing in A. Fans turn on, but receiving no picture to monitor.

    As I have said before, I find it weird that the gfx ceased working after I put back the PSU. I think the two are linked somehow but I can't figure out how. I put back the 20 and the 4 pin connectors to the mobo and the rest to the drives.

    I also noticed the mobo had a 24 pin connector but I tried all the possible combinations and the 20 pin connector only fits in one way so I'm confident that is not the problem.

    I am intrigued because as I said before the heatsink fan on the graphics card is still spinning on boot as well.
  5. kimsland

    kimsland Ex-TechSpotter Posts: 14,523

    Can you try B PSU into A again (now you've got me talking this way)

  6. nimbus_racing

    nimbus_racing TS Rookie Topic Starter Posts: 29

    I don't get it, what would that prove? Computer A worked with PSU from B. I got a new power supply for A and it's running fine now.

    I'm pretty sure B PSU is good. It was working 100% before the test swap, worked in computer A and is working now (fans are spinning when I on it).
  7. kimsland

    kimsland Ex-TechSpotter Posts: 14,523

    Sorry I missed something, your screen is blank isn't it?

    If so, I'm asking you to try the known working power supply (ie the new one might be faulty - yes true - even though it turns on and all)
  8. kerz

    kerz TS Rookie Posts: 20

    The board you have needs power to all 24pins plus the extra 4port pin to the CPU.
    Your Vid card probably needs power hooked up to it as well. look on the back of it. It should have a power hook-up like you would find on a hard drive.

    The extra 4ports on the mother board supplies extra power to the PCIe slot
    A 20pin won't cut it. You'll still get power to the board but the PCIe slot will be under powered
  9. nimbus_racing

    nimbus_racing TS Rookie Topic Starter Posts: 29

    what do you mean? there is no direct link from the PSU to the gfx card is there? (lol. noob). The heatsink fan is spinning so the gfx card is getting power of some sort.

    kimsland - the psu in the computer without picture is the psu i used to test the other computer. so I am sure that is in working order.
  10. nimbus_racing

    nimbus_racing TS Rookie Topic Starter Posts: 29

    in reply to your edited post kerz...

    the psu has 20 pins into a 24 pin slot and an additional 4 pin connector. I know this psu works with this mobo so I can't see the 20/4 pin connector being the problem. there are no molex style connections coming from my gfx card.

    I've decided to throw in my 8600gt from my other computer (computer c) and see how that works...
  11. kerz

    kerz TS Rookie Posts: 20

    Check my last post (refresh the page) I edited it while you were posting your last one.

    Even if you only have 20pins plugged in your still going to get power. Sometimes a blown Power supply can make fans run and even power the HDD's and DVD. It just depends on what part of the board is getting power and what part of the power supply is blown .... If your board is not getting power to all the right places then you will not get a picture

    If the main power on the board has a 24pin hook-up, then you need to have all of them hooked up. Including the one for the CPU

    Most new vid cards need power plugged directly into them. I have had over 4 Vid cards that took power directly from the power supply. If the card is a lower end card then it won't need the power supply hook-up.

    Depending on your card it might even take a SATA power connector, Mine does.
  12. nimbus_racing

    nimbus_racing TS Rookie Topic Starter Posts: 29

    8600gt into the computer didnt work either.

    and i double checked, definately no molex connectors on either of the cards, only another gold contact on the opposite side (which I have been told is for SLI and hence not relevant).

    you say that if the mobo has 24pins, ALL 24 pins must be occupied. From memory this is what I recall and how it is currently set up.


    Note: due to the nature of the patterns on the 24 pin slot on the mobo, the 20 pin connector could only be inserted in that manner (i.e. will not sit with 1 row of vacant pins on either side or 2 rows of vacant pins on the opposite side)

    this is weird because this power supply DEFINATELY worked with this computer before. So unless someone took 4 pins off my 24 pin connector and made it a 20 pin connector I am puzzled!
  13. nimbus_racing

    nimbus_racing TS Rookie Topic Starter Posts: 29

    By the way, these are ALL the connections from the PSU. Obviously the 20 pin and the 4 pin and a whole bunch of molex.


    I am honestly stumped. Tested two graphics cards, two screens, two vga cables and the system is definately getting enough power for the cpu and gfx card fans to spin. What the bloody hell could it be? :mad: :mad: :mad:
  14. kimsland

    kimsland Ex-TechSpotter Posts: 14,523

    I'm getting more confused too (along with everyone else I suspect)

    You need all 24Pins plugged in
    You also need another 4 Pin plug for the CPU

    But that PSU doesn't have that

    By the way what's that PSU wattage rating?

    Just get the full 24Pin PSU (they usually have sata power too)
  15. nimbus_racing

    nimbus_racing TS Rookie Topic Starter Posts: 29

    I know it's hard to follow. I don't understand why you need all 24 pins plugged in. I know 100% this psu worked before as it appears now (i.e. a 20 pin and a 4 pin). It's a 400w.

    I'm on the hunt for a newer 24pin psu now to hopefully end all this...
  16. kimsland

    kimsland Ex-TechSpotter Posts: 14,523

  17. nimbus_racing

    nimbus_racing TS Rookie Topic Starter Posts: 29

    I know I'm beginnning to sound like a broken record, but the thing is this PSU worked fine as I have it now, without any such adapters.

    Apart from the PSU, is it possible any other hardware components may be causing this blank screen?
  18. kimsland

    kimsland Ex-TechSpotter Posts: 14,523

    You've had both, I feel
  19. nimbus_racing

    nimbus_racing TS Rookie Topic Starter Posts: 29

    It has to be some conincidence for 2 PSU's to die in two days.

    Here in this link ( my 20 pin looks exactly like it does in that bottom pair of pictures.
  20. kimsland

    kimsland Ex-TechSpotter Posts: 14,523

    Your video card just needs more power

    The extra 4pins (12V) will make it work

    The 20 pin power supplies may still be ok (in a less demanding system)

    You have:
    3d video
    dvd drive

    You need more power (ie 24pin
  21. nimbus_racing

    nimbus_racing TS Rookie Topic Starter Posts: 29

    I understand what you are saying, but how does that explain everything working before with the same PSU?
  22. kimsland

    kimsland Ex-TechSpotter Posts: 14,523

    Because you touched it (and that's the truth of it)

    It must be the M/B or the card or something is drawing, ever so slightly, more power
  23. nimbus_racing

    nimbus_racing TS Rookie Topic Starter Posts: 29


    I'll go out for a new PSU and let you know the results of that.
  24. kerz

    kerz TS Rookie Posts: 20

    Hey Nimbus,
    Let’s put some things to rest:
    The power supply worked in the other computer because it only needs the 20pin connecter on the main power.
    Boards that have a 24pin connector with only the 20pin installed, (like you have here), will run everything including (in some cases) onboard \intergraded Video. BUT the extra 4pins on the main power connection on your new board are dedicated to the PCIe slot. Just like the extra dedicated 4pin connector for the CPU (shown in your picture, black and yellow wires just above the main power ).
    If you don’t plug the 4pin connector in for the CPU, the board won’t boot but the CPU fan will spin and everything else will power on.

    So, in conclusion..... If the extra 4pins on the main power connection are NOT hooked-up, the card won’t do anything but spin its fan.

    Trust me I’ve been doing this for over 10 years. :) Ok, don't trust me too much, everybody makes mistakes. Though I’m 99.99999% sure this is the problem.

    I just hope the card will be ok after taking it apart. While your pick'n up a new PSU, get some thermal paste if you can, just in case your card starts overheating, you may have to goop-up the heatsink. I would also download a Temperature App to monitor your cards Temp while playing games.

    Think of it this way:
    Once everything is settled and you stop hating your PC, you will have learned more in this short time than someone who only knows how to replace their Video Card. And you get bragging rights because you learned the Old-Fashioned way

    Hope everything works out for you. Good-on-ya for persevering.:grinthumb
  25. kimsland

    kimsland Ex-TechSpotter Posts: 14,523

    You did read this didn't you:
    But I've already commented Why above
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