Installed a new CPU/heat sink - PC not starting up

I just installed a new AMD 1090T on a ASUS M3A78 EM motherboard and now my PC is not starting up.

I checked and ensured that all plugs and connectors are connected to my motherboard. I plugged in the PSU cable, and hit the power switch. My motherboard's LED light comes on.

I then press the power button - and nothing. No POST, no beeps, and no fans spin. Only the motherboard light comes on.

This is what I did:

I updated the BIOS prior and the latest BIOS support the 1090T CPU. I've used this PC fine for a month or so with these BIOS.

I turned off my PC, turned off the power and unplugged it. After waiting for a few minutes, I opened it up and unplugged all plugs, video card, PCI cards ect.

I then removed my motherboard. Next I removed a Sunbeam Core Contact 120mm heat sink/fan - this took a bit of effort, had to physically remove motherboard before getting it off.

I then removed my 9950BE and installed my new 1090T and 92mm Xigmatek LOKI heatsink/fan with TX2 thermal compound.

I am concerned the motherboard might have got damaged during the process of removing and installing my CPU heatsink. But the light on the motherboard comes on when I plug in the power, does that mean it is not a motherboard-related issue?
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  1. I put the AMD 9950 back in, and it POST and went into Windows fine. I tried the 1090T again, and it still did not work.

    I decided to put the 9950 back in, and now it does not POST with the 9950 either.
  2. Treat the system like a new build that will not boot.

    Work systematically through our standard checklist and troubleshooting thread:
    I mean work through, not just read over it. We spent a lot of time on this. It should find most of the problems.

    If not, continue.

    I have tested the following beep patterns on Gigabyte, eVGA, and ECS motherboards. Other BIOS' may be different, but they all use a single short beep for a successful POST.

    Breadboard - that will help isolate any kind of case problem you might have.

    Breadboard with just motherboard, CPU & HSF, case speaker, and PSU.

    Make sure you plug the CPU power cable in. The system will not boot without it.

    I always breadboard a new build. It takes only a few minutes, and you know you are putting good parts in the case once you are finished.

    You can turn on the PC by momentarily shorting the two pins that the case power switch goes to. You should hear a series of long, single beeps indicating memory problems. Silence indicates a problem with (in most likely order) the PSU, motherboard, or CPU. Remember, at this time, you do not have a graphics card installed so the load on your PSU will be reduced.

    If no beeps:
    Running fans and drives and motherboard LED's do not necessarily indicate a good PSU. In the absence of a single short beep, they also do not indicate that the system is booting.

    At this point, you can sort of check the PSU. Try to borrow a known good PSU of around 550 - 600 watts. That will power just about any system with a single GPU. If you cannot do that, use a DMM to measure the voltages. Measure between the colored wires and either chassis ground or the black wires. Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. Tolerances are +/- 5% except for the -12 volts which is +/- 10%.

    The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.

    You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.

    A way that might be easier is to use the main power plug. Working from the back of the plug where the wires come out, use a bare paperclip to short between the green wire and one of the neighboring black wires. That will do the same thing with an installed PSU. It is also an easy way to bypass a questionable case power switch.

    This checks the PSU under no load conditions, so it is not completely reliable. But if it can not pass this, it is dead. Then repeat the checks with the PSU plugged into the computer to put a load on the PSU.

    If the system beeps:
    If it looks like the PSU is good, install a memory stick. Boot. Beep pattern should change to one long and several short beeps indicating a missing graphics card.

    Silence, long single beeps, or series of short beeps indicate a problem with the memory. If you get short beeps verify that the memory is in the appropriate motherboard slots.

    Insert the video card and connect any necessary PCIe power connectors. Boot. At this point, the system should POST successfully (a single short beep). Notice that you do not need keyboard, mouse, monitor, or drives to successfully POST.
    At this point, if the system doesn't work, it's either the video card or an inadequate PSU. Or rarely - the motherboard's PCIe interface.

    Now start connecting the rest of the devices starting with the monitor, then keyboard and mouse, then the rest of the devices, testing after each step. It's possible that you can pass the POST with a defective video card. The POST routines can only check the video interface. It cannot check the internal parts of the video card.
  3. According to ads on Newegg, the board is a socket AM2+/AM2 and the chip is an AM3.
  4. Thanks for the reply. There where two issues:

    1) Removal of the Sunbeam 120mm destroyed the original motherboard.

    2) The AMD 1090T was a defective.

    Bought a new motherboard and while I got beeping issues and error lights, the PC would not get into the BIOS. Getting a replacement CPU from Amazon (took me two days) finally fixed the issue. No reinstallation of Win 7 Pro upgrade was required.

    Lesson learned: Don't buy a Sunbeam product!
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