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No mobo light, new PSU, new mobo

By bobfredstan ยท 13 replies
Oct 30, 2010
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  1. I installed a new motherboard, and it does not seem to be getting power. The green light is off.

    When I first installed the motherboard, it was connected to the old power supply. When I would plug it in, I got a clicking noise, but nothing else. I figured since it was only a 250w psu, and motherboard manual states 400w+, I put in a 500w power supply. Now I get nothing. Not even clicking noises. The whole thing wont even run POST. Literally, nothing happens when I plug it in, or click the power button. Yes I tried the switch on the back of the power supply. It's active PFC.

    I just installed a P5G41-M LX2 motherboard
    I installed a 500w OCZ stealthxstream2 power supply

    I already connected the 24 pin and the 4 pin power cables.

    Can anyone please give me some advice? (to at least get the green light on)?

    I would try a new processor or new ram, if this showed any signs of power going to the motherboard at all.
  2. captaincranky

    captaincranky TechSpot Addict Posts: 14,363   +3,594

    Well, I don't know about a motherboard that requires "400 Watts". I think that the CPU, and even more importantly, the graphics card combine to set the tone of how much power is likely to be drawn.

    Moving along, the "clicking" you heard could be the PSU cutting out due to a short circuit. Check the board to case standoffs, and make certain every one you have in place, has solder lands under the screws. (These are intended to be grounded). If there is no solder land under a screw, remove that particular standoff. BTW did you hook up the ATX (4 pin) connector, the plug near the CPU, and did you connect the PCIE- 6 pin connector to the video card? (This assumes the card you're using needs one)

    That bad news is that you may have damaged the board, if indeed it was a short.
  3. bobfredstan

    bobfredstan TS Rookie Topic Starter

    the motherboard has onboard graphics, which is the only thing that I am using, so no extra power is needed for a graphics card. Anyway, what did you mean by, "Check the board to case standoffs, and make certain every one you have in place, has solder lands under the screws. (These are intended to be grounded). If there is no solder land under a screw, remove that particular standoff." Let me rephrase, what is a "case standoff", and what is a "solder land".

    I really appreciate the help, but I don't know what all of the terms mean, thank you.

    Also I did not mention that I am working on a pre-functioning computer. The computer is HP, and I hate hp now, but it's what i'm working with. However, the replacement motherboard is extremely similar to the previous one, and all of the holes had a corresponding area to place a screw into (if that helps at all).
  4. captaincranky

    captaincranky TechSpot Addict Posts: 14,363   +3,594

    The case standoffs are the small brass tubular thingys that screw into the case, then the board screws go into them. "Solder lands" are usually a ring of solder dots, surrounding the mounting screw hole in the mother board. Unless a mounting hole has these solder dots, do not use it.

    The next question would be, where do you think the clicking was coming from? A HDD can click when it starts, as perhaps a PSU can click if it has a protection relay or such in it.

    I missed the "G41", as these are all integrated graphics boards, which would have also saved some typing. Still, it goes to the fact that the board doesn't really need 400 watts to function.

    Since this is Intel socket 775, what are you using for a CPU cooler? The push pin mounts can give people trouble, and if the cooler is loose, the system will shut down in a big hurry.

    If you have a digital voltmeter, you could check to see if the proper voltages are present in the PSU harness, while it is unhooked from the board. You will find 3, 5, and 12 volt wires in the harness.

    Make sure that the CPU is in the socket correctly, and also that none of the wires have backed out of the 24 pin block, and that it's seated properly in its socket.

    The "it clicked at first, now it doesn't even do that" is not very encouraging. Bear in mind that an improperly seated CPU, or stick of RAM can take out a board. How many RAM sockets are on this board, 2 or 4? if you're using only one stick, it has to be in the proper socket, and that same socket must be populated, even with two sticks installed. See the mobo manual for the correct arrangement.

    Here are a couple of guides for "no post"; https://www.techspot.com/vb/topic155806.html#post954666 and https://www.techspot.com/vb/topic113137.html

    Why did you replace this board in the first place?
  5. bobfredstan

    bobfredstan TS Rookie Topic Starter

    Every screw has a "solder land" and a case standoff. The clicking was coming from the power supply. The hard drive was not plugged in, I was just trying to see if I could even get fans to spin or any sign of life, which did not occur. I am using a cpu fan for cooling, and the system will not even do anything, so it can't "shut down in a big hurry", so I doubt that's the problem. The power supply is supposedly "whisper quiet", so perhaps the clicking is the same, but I can't hear it (maybe)?

    ON THE 24 PIN BLOCK! I have noticed on the past 2 power supplies that there is one hole which looks like there is absolutely nothing in it. Could this be a "wire backing out" issue? It's the same hole on both, I believe it's the third one from the right. There are two sticks of ram installed, there are two sockets. What do you mean that they must be "populated", and wouldn't it beep if the ram was not installed correctly? Like I said, it does nothing.

    I replaced the board because the computer would not boot, and there was a "no video" signal on the monitor. Technical support said that it was the motherboard and we need to send it in and spend 400 dollars to get it fixed. I tried many things to make sure that it wasn't the RAM, or the CPU being loose, and a few other things, but I eventually just decided that it was probably the motherboard, since all else failed. Even power supply and motherboard connected (also with onboard graphics), it would not boot. Fans would spin, but there was no display.

    actually, upon further inspection, there is no wire even going to that hole, is that normal?

    the power supply claims to have short circuit protection, so is it possible that my motherboard isn't destroyed?
  6. CCT

    CCT TS Evangelist Posts: 2,610   +6

    Until captaincranky gets back, you can see from the diagram here that a 'blank' place in position 20 of the 24 pin power connector is normal.


    edit: and, if you swapped mobos, then identifying the exact model of the HP helps to then compare the 2 motherboards for overall compatability
  7. bobfredstan

    bobfredstan TS Rookie Topic Starter

    Ok so the previous motherboard was a Foxconn mcp73m02h1 from an HP Pavillion a6600f computer.

    Thanks CCT, that diagram cleared things up, and my 20+4 pin adapter is fine. How likely is it that the 24 pin socket is nonfunctioning? I took out the adapter and put it in to the motherboard's socket several times, but is that possible to make some connection loose?
  8. captaincranky

    captaincranky TechSpot Addict Posts: 14,363   +3,594

    Not likely at all. The pins in the board have no place to go, so any problems would be in the PSU plug. Sometimes the pins in a molex type plug can release when trying to plug them in. You would probably see the metal end of a pin hanging out of the plug, should this have occurred. This happens when the pins have not been pushed all the way in until they lock during assembly, and not staying put when being plugged in would be the result.

    I suggested that you try to ge a hold of a PSU tester, and probe the PSU plug for the presence of the required voltages, how is that progressing?

    I find it odd the you have the same problem, or at least a variation of it, that you did before the board was replaced. This makes me wonder if the diagnoses was sound in the first place.

    The PSU clicking still disturbs me. Even if it has a mechanical relay for short circuit protection, that would click once after the capacitors charge, and no do so again, unless there was a short. There's no earthly reason for clicking, in a working installation.

    Unplug the ATX CPU plug (4 pin 2 blk, 2 yel), and see if the fans fire up then.
  9. bobfredstan

    bobfredstan TS Rookie Topic Starter

    i'm thinking of going out to a computer store near me, Microcenter, tomorrow or the day after to get a psu tester, do you think they would sell them there? hopefully not too expensive. Also, this psu does not click, I am trying to get the system to work with the new psu.

    I referred to this, but apparently this person's motherboard was defective:


    I hope that isn't my problem
  10. bobfredstan

    bobfredstan TS Rookie Topic Starter

    sorry that I haven't been able to make enough progress today or yesterday, I have a test tomorrow in my microeconomics class (one of those annoying required classes), but I should be able to work on it religiously after tomorrow
  11. captaincranky

    captaincranky TechSpot Addict Posts: 14,363   +3,594

    Frst bobfredstan, use the edit button to assimilate, "afterthought into thought", instead of a second post. No biggie though.

    Microcenter has everything else, I don't see a PSU tester as being out of reach. A bad mobo is certainly a possibility, but again, I'm confused by the fact that you have some of the same symptoms. Some people are that unlucky, you might be one of them, who knows?

    Microcenter shows 2 units; http://www.microcenter.com/search/search_results.phtml?Ntt=PSU+tester&N=0&submit.x=0&submit.y=0 Whether or not they're in any given store ATM is another matter. Obviously, you can check it out.

    You might try unplugging any fans going to the board, as there could be a short in one of them.
  12. bobfredstan

    bobfredstan TS Rookie Topic Starter

    The case has raised areas on which the motherboard rests and a screw goes into. It can best be described as a "volcano"-type structure, in which it is a raised mound with a hole in the middle. Can this be classified as a standoff? Or do I need to buy actual standoffs? I noticed that the previous motherboard functioned perfectly fine without any additional standoffs.
  13. CCT

    CCT TS Evangelist Posts: 2,610   +6

    Since each manufacturerer makes differentn designs of BOTH mobos and cases, the odds of getting an exact match for where to attach WITHOUT standoffs is like, well, extreme.

    So, that is likely your issue.
  14. bobfredstan

    bobfredstan TS Rookie Topic Starter

    Well thank you everyone for trying to help. I was trying to fix my mother's computer. My uncle told my grandma that her computer was slow, so she went out and bought a new one. Then she told my mom, and she told me, and I said that I'll look at it (since she was throwing it out anyway). So then I put my mom's hard drive into my grandma's computer, installed 3 gigs of ram, and a new video card, and everything worked great. CCT, you are probably right about that by the way, HP sucks in that regard, and they don't allow their parts to be largely interchangeable with other companies' parts (which is why they could make people pay 400 dollars to get the computer fixed, 100 for diagnosis, and 300 to fix it).

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