PC will not Boot

Is it true that if the heat sink is not properly attached to the processer and the CPU fan is not plugged in, it will fault and will not let the pc boot up? Is this a safty feature the some Asus motherboards retain?
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  1. Are you getting any kind of post at all, or are you just getting a black screen with no beeps? If it's just a fan error there's ways of circumventing that issue. Do you have an after market fan, or what's the deal? Please list full system specs.
  2. yea its true about the plugging thingy (cable) . actually that on every mobo not only asus , and its will give a blank screen . but as the heat sink is not attached its will be boot up but you will suffer overheat issues
  3. My question for you is why are you trying to start your PC without a heatsink/fan properly attached on your CPU? This can cause problems in itself.
  4. thats a sure fire way to getting an expensive BBQ on the go i guess, sorry but the tech gods will not allow such an abomination to occur. Its not a safety feature for the PC but for you!
  5. mkgli4 said:
    Is this a safty feature the some Asus motherboards retain?

    No. It's a safety feature of the CPU.

    Make sure that the heatsink is properly installed and the fan is plugged into the CPU fan connector on the motherboard.

    If you still cannot POST ...

    Work 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 beeps patterns on Gigabyte, eVGA, and ECS motherboards. Other BIOS' may be different.

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

    Breadboard with just motherboard, CPU & HSF, case speaker, and PSU. You do have a case speaker installed, right? If not, you really, really need one. If your case or motherboard didn't come with a system speaker, you can buy one here:

    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.

    Motherboard LED's mean very little. When on, all they are telling you is that the computer os plugged into a live power socket and the PSU is switched.

    Remember, at this time, you do not have a graphics card installed so the load on your PSU will be reduced.

    If no beeps:
    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.

    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 or long single beeps indicate a problem with the memory.

    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.

    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.
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