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Upgraded comp will not start. Mobo LED lights up.

By Daed ยท 9 replies
Oct 21, 2008
  1. Greetings,

    After apparently one of my motherboards decided to stop working I decided to upgrade my computer, and finally learn how to build one myself.

    A bit of backstory on this:
    Since I have warranty on the old motherboard, they took it in order to test it but they have not managed to test it yet. Basically over the course of the week before it died I kept having more and more hangs and missed POSTs, and eventually it stopped POSTing every time. Either way once we opened it up we found one of the little fans (probably the southbridge cooler, I'm not sure) stopped working. The keyboard also was not receiving power, but the motherboard LED would power on. (OTT the motherboard was an A8N-SLI)

    Now, I bought a e8400, 2X1gigs of 667mhz patriot ram, and a P5KPL-CM motherboard. I specifically wanted a microATX board since I probably will buy a LANbox later on.

    Now this is the first time I'm putting something together, but I've done a LOT of reading up on this subject and used the utmost care when putting it together.

    While I was putting it together I realized that one of the screwholes on the motherboard did not have a corresponding spacer hole under it. I decided to leave it without a screw, thinking it is unimportant.

    The LG775 cooler was kind of hard to push in though, I was worried I might crack the board pressing it down!

    Now once everything was put together I plugged it in, pressed the power button, and heard a small chirp. Oh dear.

    After thinking I shorted something and panicking a lot, I double-checked everything to make sure I did not cause any horrible damage to the motherboard because of some gross mistake I've made. I couldn't find anything done wrong, but noticed the following things:

    - Two of the top cooler pins are inserted, but seemingly not all the way. Like I said I was worried about pushing down hard upon them, hearing the motherboard creak like that. The CPU did have preapplied paste on it.

    - The power led plug from my chassis is three pins wide, but my mobo only has two pins one next to another. I decided this is not critical and never plugged it in.

    - The power led on the motherboard lights up when the PSU gets power, but like I said, fans do not spin up, no activity when I even try to short the power pins with a screwdriver.

    - No visible damage (burns, cracks, etc)

    Now, I have realized that the PSU might be the problem since my last motherboard exhibited similar symptoms, but the reason why I came here is that I am worried that I might have caused damage to the motherboard or CPU somehow.

    Is a slight cooler misalignment enough to cause the motherboard to not start up at all? Or any of the above things? What I am thinking right now is that one of the rails coming from the PSU is dead, powering up the internal LED but not giving enough power to start it up. I just want other people's opinions on this, since I'm really worried I might've blown up about 400$ worth of upgrades.

    Thanks in advance, guys.
  2. CCT

    CCT TS Evangelist Posts: 2,610   +6

    IF the cpu heatsink is not properly attached boot failure is likely (actually, it is the Intel CPU thermal protection shutdown action that is happening).

    You Asus manual shows the precise holes to use for the stand-offs.
  3. Daed

    Daed TS Rookie Topic Starter

    Yes, I can see the screw holes on the motherboard just fine, problem is one of those holes does not have a standoff hole on the chassis under it. There isn't even a hole near where the motherboard hole is.

    Also, if the CPU heatsink would be improperly placed I would at least expect the motherboard to power up for a second before seeing the CPU temperature going skyhigh. I have managed to put in the last millimeter of the two pins that didn't want to go in, but I don't want to start the motherboard up now for fear of damaging something even further.

    Like I said, what worries me is that the motherboard does not want to start up at all. It might be the PSU but I want to know if I can tell if the motherboard or CPU is damaged in any way. :eek:
  4. CCT

    CCT TS Evangelist Posts: 2,610   +6

    You have the 24 and 4 pin power supplies hooked to the mobo?
    You have the psu set for 120v (if in NA).
    You have the ram fully seated?
  5. Daed

    Daed TS Rookie Topic Starter

    Yes, I'm not stupid. :haha:
    PSU doesn't have a power switch, it's 220v as usual, I'm in the EU.
    Ram is seated and firmly held in place.
  6. gguerra

    gguerra TS Guru Posts: 314

    Is your CPU fan connector plugged in and is the CPU fan turning on. If it is not then the CPU will not function more than a couple of seconds. You MUST have good contact between the metal part of the heatsink and the top surface of the CPU. Make sure all power connectors are seated properly and if they are and you still have no fans on then look at your PSU. The connector for the CPU Fan should have at least 3 prongs on it if it has 4 it is a variable speed fan control, make sure to align the right pins. There are other things you can try such as swapping the RAM oh and dont worry it's pretty hard to damage the CPU due to heat since it will shut off by itself.
  7. Daed

    Daed TS Rookie Topic Starter

    4pin cpu plug was going into the motherboard, notch aligned, when I turned it on since the start. As I said, nothing did want to happen - no fans, no HD activity, - when I first tried to turn it on.

    Can faulty ram out of the factory simply make a motherboard refuse to power up even the fans?

    Though I have been thinking, if the PSU has failed on me, there is a chance of it frying a lot of things if the voltage spiked on a few of the rails...sure hope that didn't happen.
  8. gguerra

    gguerra TS Guru Posts: 314

    I had the same thing happen to me recently with where the Mobo led would light but nothing else and it was the PSU. I'm not saying that is your issue but just because the LED will light does not mean all of the other connections are providing the correct voltage. Best way to test is with a volt meter or swap out the PSU whatever is easier. It could be bad RAM, not ruling that out but if your LED lights up and none of the fans do then I would look at the power supply or the motherboard itself.

    Edit: If you disconnect the power supply from the mobo make sure to leave the power switch connected so you can power it on from the front and test the voltages
  9. Daed

    Daed TS Rookie Topic Starter

    Update here.

    My suspicions were correct, the PSU was dead. But apparently when the PSU decided to die it took out something else, probably my GPU as nothing was showing up when I was turning on the system with another PSU.

    Thankfully I've got both on warranty, and the first time I tried to install the new components I didn't break anything.
  10. Tedster

    Tedster Techspot old timer..... Posts: 5,746   +14

    your psu is probably shot. test it with a psu tool and a multimeter.
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