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Is my PSU kaputt?

Last response: in Components
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March 6, 2006 2:44:07 PM

Hellow, I own a Zalman Z300B power supply, which was provided as a warranty replacement for a burnt Z300A. over 1.5 years ago.

Currently I am having a problem booting my computer. The problems began yesterday, while I was watching TV from my TV card. The computer suddenly froze! No responce, not even to CTRL+ALT+DEL. So I pressed the rest button, the screen went blank, but the computer didn't boot. No BIOS message, no beeps from the motherboard. The LEDs were working however. So I closed the back button of the power supply and left it there for a couple of minutes. Then I turned the power back on and the computer booted, upto to the Windows loading screen where it froze again.

This time, removing the power and/or turning the switch off didn't help. The monitor didn't get any signal. So I removed the graphics card, all the RAM and all the PCI cards I had installed. Normally I should have been getting beeps, but I didn't. I tried to remove the power cable several times and at one time, I managed to get the system to beep. But after that one time the PC still wouldn't boot.

So from my observations the problem should either be the power supply, or the CPU. But if it was the CPU, it should have been completely dead, it shouldn't sometimes boot and sometimes not...

What do you think?

More about : psu kaputt

March 6, 2006 5:30:48 PM

do you have a spare power supply around? why dont you try that if you do?
as a note, it could also be the motherboard seeing as something could have blown out on it.
March 6, 2006 5:34:43 PM

I would agree to try another PSU.

Also I'd check for any burnt traces on the Memory, Power Molex's, and expansion cards.
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March 6, 2006 6:01:25 PM

why would it be the PSU?

its your PC is freezing then the PSU is still powering ur PC right?

now ir PC just shut down then it may be ur PSU i think its a MOBO problem maybe your RAm
March 6, 2006 6:30:51 PM

Why not the PSU?

I've seen a PC leds light up, no display, no beeps, all fans spinning, but yet.. the CD-ROMs would not open.

Later on.. I found a burnt trace on the memory dimms.

But for that.. the motherboard and PSU was pretty much fried.

Edit: could also try putting the PSU on volt meter if you have one, or tester for around 12-19 bucks.
March 7, 2006 8:38:17 AM

Hellow guys, thanks for the info...

1. I have tested the PSU with a digital Voltometer and the readings appear fine. However, that only means I am getting the correct voltages, not that enough current is flowing to the CPU.

2. I removed the motherboard and tried to find through it if anything was burnt, but nothing. Everything looks new and ok. (I have seen burnt parts on motherboards before and I certainly don't see on this one).

3. It is not the RAM, because I set, I completely removed them and I don't get a beep for the missing RAM. I did get it once though, but after restarting it stopped. So the problem is before the BIOS even checks for RAM.

4. I have made a notice, which might prove that it is a power supply issue: Although the CD-ROM leads up and the tray opens, if I put a CD inside, it won't spin it. TO second that, I realised that neither the HDD spins up! In fact after pressing the button to shut down the PC, I can hear the brake in the HDD engaging, but it doesn't spin down as normally.

Now, if these devices would only spin up at the request of the BIOS, then it means nothing, but if they should have done it, then it means they are not adequate power... What do you think?

PS: Unfortunately, I can't test the components individually, as everybody in this University has an Athlon system! :( 
March 7, 2006 9:49:28 AM

It does sound like it could be the PSU but it might also be the motherboard.

It is possible the PSU may have died and taken the motherboard with it.

I would recommend replacing both.

Good luck
March 8, 2006 6:46:10 AM

Quote:
Hellow guys, thanks for the info...

1. I have tested the PSU with a digital Voltometer and the readings appear fine. However, that only means I am getting the correct voltages, not that enough current is flowing to the CPU.
The supply regulates the voltages, not the currents, which are determined by the load, which in this case is the computer. If you measured under realistic conditions, that is, with the computer running and at the power connectors in use, then the motherboard is receiving correct voltages. However the CPU may be another matter because it takes +5V or +12V from the supply and converts it down to the CPU voltage through a regulator on the motherboard. The main reason that regulator fails is because its electrolytic capacitors (standing metal cylinders wrapped with plastic) have failed (may bulge or leak when this happens). The CPU voltage can be measured through the pins or tabs of the MOSFETs, and at least one will have CPU voltage riding on it. If you attempt this, take care not to short anything.
March 8, 2006 9:31:54 AM

Thanks guys for all the replies... Unfortunately it is not the PSU because I have tested a brand new one from a friend and still nothing happens.

The motherboard's electrolytic capacitors, appear OK. At least from the look of them.

I cannoit carry any more testing myself, so I will be sending the processor back to be chacked by the shop I bought it from. Likely intel provides 3 years of warranty for boxed products. If it isn't the processor, then only the motherboard remains... Asus does provide 3 years of warranty, but I have lost the original receipt.

Just another question though... Would the motherboard beep if no processor was present, or does it need the processor to beep?
March 8, 2006 10:53:42 PM

It is probably the motherboard. Even ASUS boards die :-(
March 9, 2006 9:25:46 AM

Supposed it is the motherboard, what motherboard do I buy?

Do I get a new i865PE based, propably a P4P800 series again, or should I go for a VIA PT880? I find the presence of both AGP and PCIe appealing, as I was thinking of upgrading the graphics card later when Vista ships.

PS: I've also opened a new topic in mainboards for that...
March 9, 2006 10:30:55 AM

Well some people hate VIA... so expect to hear a lot about that...

Intel boards are not my specialty but I did build some machines with Asus P4C series boards -- they were ok.
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