PC doesn't reach POST - new motherboard/CPU?

  ? DP ? 15:05 10 Feb 2004

I really need some help with this one. My PC started playing up a couple of weeks ago and got halfway through the boot-up process before switching off. It never reached logon and gradually got worse, now nothing happens at all. If I try to switch on, then the case fan, PSU fan and CPU fan all rotate a couple of times and nothing else happens. Nothing appears on the screen.

I have tested all the drives in another PC and they work fine. The RAM is healthy and whatever combination of components I try to start up with nothing happens. I originally thought the problem may be a faulty and underpowered PSU (250W that came with the system) but this was also not the problem.

I have come to the conclusion it must be the motherboard or the processor but I have no idea how to tell which is at fault, if that is indeed the problem....any advice would be hugely appreciated -and hopefully save me a few £££-!!!

The motherboard is a GA-7VKML (VIA KM266 AGPset) about 18 months old, came with a "Time" system, using an AMD Athlon 2000+XP CPU.

  Diodorus Siculus 15:17 10 Feb 2004

CMOS battery perhaps?

Have you tried to change the jumper on the mobo to clear the CMOS?

  SEASHANTY 15:17 10 Feb 2004

Sounds like a dying PSU. Did you test the CPU by substituting a new one or known good one - say about
350 or 370 watts?

  georgemac 15:19 10 Feb 2004

the motherboard is more likely to have failed than the cpu, as long as you have not been overclocking and the temperatures have been OK.

I had similar problems, except it did not die completely but kept crashing, the giga-byte motherboard was faulty - well it must have been cause I replaced it and all has been OK since.

Because I was not sure, I bought a used asus motherboard from ebuyer to check a7v333 for £20 and I am well chuffed with it.

I prefer ASUS - quality boards in my experience.

  SEASHANTY 15:19 10 Feb 2004

Oops not substitue the CPU. It should have been PSU.

  georgemac 15:22 10 Feb 2004

click here only used asus in stock - when I read your post I too initially thought the psu was the problem, why are you sure it is OK, I always have at least 300 watt psu on athlon systems, and preferably higher (this one is 450watt)

  ? DP ? 15:37 10 Feb 2004

I tried shorting out the CMOS by using a jumper and removed the battery for about half an hour. This made no difference I'm sad to say.

As for the PSU, I was convinced originally that this was the problem as it was 250W which was just enough for the new system on max power but with upgrades I am using nearer to 400W (should everything be running a it's peak). Tried a new 480W PSU which made no difference.

Haven't actually tried removing CPU as I'm not sure what I would be looking for if I did that. The heatsink had accumulated a lot of dust but I have been told by some people it is more likely the motherboard than CPU. Is there any way of knowing for sure so that I don't end up buying components I don't need?

  SEASHANTY 16:15 10 Feb 2004

I think motherboards are akin to TV circuit boards and the only test these days is by substitution of a known good board. Similarly the CPU is best tested in another PC to confirm operational. Some computer
shops will test them for you for a nominal charge.
Otherwise disconnect everything except the basics of
M/B, with CPU, Graphics and HDD and floppy drive. If it won't boot with the basic components then you have a good idea of what could be faulty. It could also be a faulty on/off switch on your PC.

Post is a low level test conducted in two parts.The first tests that the basic hardware .i.e. cpu ,RAM and video card are ok before going on to a test confirming the monitor is functioning as well as the rest of the hardware including the power supply.If it doesn't pass the first phase it should give an audible beep. If your computer switches off before completion of post, it is probably, as you have guessed either the power supply of the cpu.
As a start, I would suggest that you replace the power supply with your original one, just to eliminate a faulty new one - it does happen.
If this does solve the problem, your suspects are narrowed down to one or more of the following.
DMA Controller
Interupt controller
Memory ROM
Video card and or cable.

If you have an old spare graphic card, I would fit this, which if there is no change, narrows the fault down to the cpu or motherboard. I know this seems a long way to get to the position you think you are already at, but at least you will have eliminated the cheapest and easily fixed options.
If it is a faulty battery, you should still be able to reset CMOS. As to testing the cpu and motherboard, Ii know of no easy answers, but woulf probably replace the cpu first as it is easier, and if you go for an upgrade, it would be a worthwhile purchase, if you eventually have to replace the motherboard.

  georgemac 12:01 11 Feb 2004

remove the memory - if the motherboard is OK it should beep like mad at you on post.

click here these are the AMI bios beep codes - the motherboard should tell you the cpu has failed - if there are no beeps it's likely to be the motherboard.

  Indigo 1 12:34 11 Feb 2004

Also check the 20 pin ATX connector for damage, bent pins loose wires and pushed fully home.

some useful info here click here

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