Could someone please answer this question?


If a CPU is bad, won't the PS at least turn on? I mean like the PS fan?

How about a mobo? Won't the hard drives at least spin up? If they are only power cabled and no data cabled?

I understood that a bad mobo or cpu will keep the system from posting, but fans, and HD's might spin.

I have done ALL the other trouble shooting on the board, but I need to know this to proceed from here.

This is a brand new system and I am trying to get some RMA's going and I think it is the PSU.
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  1. I don't think other hardware will run if the cpu is dead . You have to know that it rarely die. The best way to know if you psu is the problem is to try with another one. Even a little one without all your stuff on your motherboard

    Gl with that
  2. all right, it is certainly been a mystery and a real pain.....I have a replacement coming from Amazon Monday. I will know then.
  3. If absoloutely nothing happens when you press the power button, then either your wall socket, power cable, PSU or motherboard is dead.

    If you have a dead CPU, some of the fans (probably PSU) will make at least a brief sign of life in order to power up the motherboard to attempt to POST.

    Does your motherboard have any LED's lit up when it's all connected and on standby? because most new motherboards do....

    If you have an LED but no response from the power button, check your PWR-BTN cable is correctly connected to the motherboard or even try manually shorting the power button pins (SAFETY - RESEARCH WHAT YOU ARE DOING FIRST!!!!) becase i've seen broken power buttons on cases before.
  4. OH, one other thing which is ridiculously daft (but I have done it once myself) if to check the power switch on the back of the power supply!
  5. Firstly get the Motherboard and power supply out of the case
    Hook up only power supply to the MB with CPU and 1 ram memory in it.
    Use your screw driver to power upby tapping the swith Pins on the MB
    If nothing happens swith off get the cpu out and check the pins for any bends put it back and make sure the heat sink is sitting properly.
    Fire up again
    Please Report Back.
  6. So it's plugged in, right?

    Have you recently connected any new hardware, peripheral or internal?

    I had this problem just recently where nothing would happen when I pressed the on switch. All I got was a blinking green LED on the mobo.

    It turned out that my mobo didn't like an audio plug I plugged in. When I switched it out for the AC '97 plug, everything spun up.
  7. Or try systematic troubleshooting. That has worked for me on a very wide range of equipment.

    Work through our standard checklist and troubleshooting thread:
    I mean work through, not just read over it.

    Breadboard - that will 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. 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. 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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