CPU or BIOS problem

[Jane]

If a computer main board does not start ( no POST) and ALL voltages( coming from PSU are correct) then, I think, the reason can be one of these:

1.Faulty CPU
2.Faulty BIOS
3.Faulty PCB

Note: By the computer main board I mean a main board itself( no hard disk or similar connected)
Is there any way how to find out which the reason ,for the failure from those named above, it is?
What measuring devices should I use and what pins to measure?

[gilly1984]

Re: CPU or BIOS problem

Faulty Ram too.

[Uranium-235]

Re: CPU or BIOS problem

could be faulty cmos too. take the battery out and put it back in

if its integrated video, try an external video card too

how do you know the voltages from the PSU are correct? are you using one of those PSU readers. Those dont' always work, cause it doesn't put any stress on the PSU, sometimes it takes a certain amount of stress on the PSU for the voltages to become unstable, which is why I always keep a solid working PSU around for testing purposes

I would try a single stick of different ram first

[brethin]

Re: CPU or BIOS problem

If a computer main board does not start ( no POST) and ALL voltages( coming from PSU are correct) then, I think, the reason can be one of these:

1.Faulty CPU
2.Faulty BIOS
3.Faulty PCB

Note: By the computer main board I mean a main board itself( no hard disk or similar connected)
Is there any way how to find out which the reason ,for the failure from those named above, it is?
What measuring devices should I use and what pins to measure?

I would say #4 Faulty Mainboard

[severach]

Re: CPU or BIOS problem

Some boards will not power on or POST without a CMOS battery. Don't forget incompatible RAM, incompatible CPU, damaged traces.

[larrymoencurly]

Re: CPU or BIOS problem

I've seen 2 motherboards that needed the CMOS battery to boot, one an ancient Socket 7, the other a Socket AM2 or 478.

I've had motherboards knock out their BIOSes, but boot block recovery always let me see something, at least if I used a separate video card, and I could usually recover by flashing from a floppy disk or USB stick. One exception was an MSI motherboard that would not load in the BIOS from the USB stick (the only recovery method it supported) and kept asking for the file that was on the stick. With that one, I had to use SPMPGM2 and flash from the parallel printer port of another computer. MSI offers 3 methods for flashing the BIOS but recommends not using the 2 methods it recommends most.

[ant3202]

Re: CPU or BIOS problem

check powersupply ......
one case.... bad psu, low voltage to startup the mainboard

imo, cpu rarely fails....

best if you can list out the pc information, like mainboard made, model, cpu, etc.