[lee_1133]

Hi,

My desktop PC was not on this morning when I got up (I leave it on overnight). Nothing happened when I pressed the power button. I then unplugged and re-plugged the power socket and it would either power up but not boot up (if that makes sense) just from plugging the power in or I could press the power button and it would come on but not load. When this happened I can then no longer switch off without pulling the power lead out of the back?

It sounds like the power unit to me but could it be the motherboard?

my PC is an Advent 3215 (from PC World)

Thanks in advance

Lee

[Mentalpen]

how far does it try and boot?

do you just get the black screen?

could be a RAM issue

[lee_1133]

The power and hard drive light come on but it never boots to a point that anything appears on the monitor (which never comes out of standby) and sometimes the PC does not come on when I plug the power in. I have to press the power button but get the same result. I cannot switch it off afterwards in either case without pulling the plug.

[bbearren]

Points to the PSU, but they are hard to check without a tester, since they get switched on by the motherboard. You may well end up replacing both.

I advise getting a larger PSU than you need, rather than a direct replacement.

[sludge3000]

When you plug the power cable in the PC's fan satrt up then turn off correct? This is a normal procedure when you connect power and a network connection to a PC, It's basicaly just become active.

You then can't turn it off without pulling the power out the abck suggesting the motherboard is not responding. I would personaly replace the motherboard but this requries removing EVERYTHING and putting it all back in again whereas the PSU is a simple job. It's up to you to decide but personaly i think it's the motherbaord causing the issue as the PC is receiving power okay.

[bbearren]

If your PC went down during the night (and there was not a power failure that knocked out the entire house), this does not indicate a motherboard problem, it indicates a PSU problem.

[Tanis]

Not entirely sure on this one, both sludge and bbearrens point seem fairly valid based on the information we have.

I have had quite a few 'dead' PC's in my time but it has never been the PSU at fault if the PC's fans come on (although it won't actually boot at all). Whenever I have had a dead PSU the system will not do anything.

But having it go off during the night would suggest a PSU fault lol.

Basically, if you get power to it and the fans start (case fans and the PSU fan that is) up I would suspect the motherboard or possibly CPU as it is that that regulates the power distribution around the other components (fans are often directly connected to the PSU).

If you do not get any fans (or they may 'twitch' when you try to turn it on) then I would tend to lean towards a PSU fault, although if the PSU has gone it could (but doesn't always) take the motherboard and/or CPU with it.

Originally Posted by bbearren

If your PC went down during the night (and there was not a power failure that knocked out the entire house), this does not indicate a motherboard problem, it indicates a PSU problem.

There may have been a power failure during the night, we don't know.

[sludge3000]

After consideration find out which parts are under warranty. If both parts (PSU and MOBO) then just get them both replaced as faulty under warranty. If only one is under warranty then get that replaced first as it is more cost effective.

[bbearren]

Originally Posted by Tanis

I have had quite a few 'dead' PC's in my time but it has never been the PSU at fault if the PC's fans come on (although it won't actually boot at all). Whenever I have had a dead PSU the system will not do anything.

I didn't say "dead" PSU, I said PSU problem. The PSU puts out different volatages for different parts of the system. Some of these voltages could be off-spec or non-existent. I have had experience with faulty PSU's that ran fans and lit lights but the PC did not boot. Changed only the PSU and that was all that was necessary.

Originally Posted by Tanis

There may have been a power failure during the night, we don't know.

Blinking digital clocks on various appliances is a dead giveaway of an overnight power failure.

[lee_1133]

Hi All,

Been out this afternoon so only just seen all the replies. Thanks to all that have contributed so far. I have now opened the PC up and I could definitely smell slight burning. At 1st I thought it was only coming from the PSU but it seems to be coming from other parts as well. I changed the PSU and the same problem occurred. The fan works & power lights up but nothing loads and I can only then switch off at the plug. The red light on the motherboard also comes on (don't know if that means anything but felt I should mention it). Could it be the processor rather than the motherboard?

[lee_1133]

Also found this...

Motherboard Information
CPU Support: Socket 478. Bus/clock speed: 533MHz / 400MHz
System Memory: 2 DDR DIMMs. Supports DDR333. Max. 2GB
Chipset:
SiS 651
AGP 4x
Onboard video embedded in SiS 730D chipset
Onboard C-Media CMI9738/4CH AC'97 audio
Form Factor: microATX - 244 mm x 220 mm

If I do need a new board can someone please provide compatible boards I can buy to replace this one if its faulty?

[sludge3000]

How old is the PC? I know PC World aint great but if you can get it repaired under warranty with them it will save a lot of hassle.

Below is pos MOBO but is first one i found so you should have a look around.

Biostar P4M900-M4 Socket 478 Motherboard

[lee_1133]

Hi, I have been away over easter so have not been able to check on the forum regarding this matter. I am pretty sure it is the motherboard as there is no 'beeb' sound when power is switched on. I have also put another PSU in with the same result. If there is no 'beeb' sound is this usually a dead giveaway that it is indeed the motherboard? If so can somebody please tell me what type of board I need as a repalcement.

(sludge3000) the PC is about 5 years old and has no warranty.

[sludge3000]

The motherboard mentioned here >>>>> Biostar P4M900-M4 Socket 478 Motherboard

Looks like a match for you current hardware configuration.

As you have already replaced the PSU then the motherboard is the most likely problem although if it was me i would save up for a little bit and get a full new kit and only keep a couple of bits from your old one i.e. HDD.

If you would like more MOBO suggestions let us know otherwise have fun with your new PC

[lee_1133]

Hi, I have just managed to remove the processor and it was burnt out on the processor and on the motherboard where it connects so I guess both are dead. I am going to just salvage what I can from it I think so thanks for your help with it but I do have another question.

I have another faulty PC which I may as well mention here rather than start a new thread.

I have not used it for about a year because I had this other PC working fine but now with both down I want to get at least one working again. This PC seems to have a faulty power button. When I press the power button on the front of the PC the processor fan kicks in for split second then stops. The PC never comes on, I've checked inside and the processor etc all look fine so it does look like a more minor issue. The PSU is not the issue as it is the same one I have been testing on the other PC. Could it be the power cable coming from the power button to the motherboard? If so how do I go about fixing it?