Mystery power-off during POST

[SimonP]

I've just built a new PC because of trouble obtaining the correct type of memory to upgrade the old one.

System spec:
P4-3.0GHz HT on an ABIT IS7-E2 mainboard.
RAM is 2GB dual channel DDR (2x1GB DDDR400 matched pair)
Video card is XFX Nvidia GeForce 6600 GT 256MB dual DVI
HDD is Maxtor 160GB SATA
DVD-RW is Toshiba SD-R5002

Other PCI cards are:
Hauppauge WinTV Nova-T (the old version)
Alcatel Speedtouch PCI ADSL modem.

The probem I'm having is that the system will just shut off during POST.

If I power on again, the system may either shut off again, or the POST will complete and then boot normally.
Once the system has booted, it will run perfectly well, even on memory and CPU intensive work.

Interestingly, this also happens on a re-boot, not just initial power-on.

The power supply is a supposed 400W unit, but the model number contains the number 330. Hmmm.

I went out and bought a new power supply, this time rated at 550W, but the model contains the number 400. Then again, it is the same make as the first one.
I don't know. Maybe they rate these things in "car stereo Watts" now?

The replacement PSU seems more reliable in starting the computer, but is no good because it corrupts the signal on the digital TV card.

Any suggestions?
Is this likely to be just a power supply problem, or more motherboard related?

The PCI cards are not to blame, as the problem existed before they were installed.

Unfortunately I do not have a spare power supply with the square 4-pin 12V connector, in order to try and eliminate the power supplies being a "dodgy brand".

Any help gratefully appreciated,

Simon.

[craizy]

I'm a bit rusty on the hardware side of things but a few things you might want to try.

If my memory works I think PSU's are rated at peak power so 500w may only have a rating of 400w at normal output might explain the stickers.

At reboot all the hardware is effectivity sent a reset singal and can cause a large surge on the psu, try disconnecting a few things and see if the fault still ocurrs (dvd, extra hds) just to see if its that.

I doubt its a short but maybe, try unplugging everything apart from the basics and slowly add items and see if there is a pattern to one device causing the failure.

If the shutdown is instant the moment you press the button that normally means a dodgie cabling or a short somewhere, have you checked the mobo seats and make sure there all ok? what else....

cant think of much else but as i said im a bit rusty but worth a try, see if anyone else has any suggestions.

Good Luck.

Craig.

--no warrenty etc.

[Miket]

Simon

Stick to what your good at, car electrics and leave computers to the boffins. :thumb:

[grahamf]

Simon
Just a suggestion - remove all extra boards from your motherboard leaving the bare essentials (video card and HDD) then test it. If it works ok then add another board and test again. Repeat for each card until the fault reoccurs. When it happens again you know the card you put in last is the culprit.
Happy fixing!
Graham

[SimonP]

Thanks for the advice!

MikeT, don't be so cheeky! :P

Graham, I had tried that, as I always test the system with just the VGA card, not even the HDD to begin with. It did shut off during the first start-up, so I checked the seating of the video card and RAM. It just seemed random after that.

The power-off occurrs about half way through POST, before the beep. The memory I have is Corsair XMS Pro, so it has those activity LEDs. It seemed that the failure would happen when all the activity LEDs were lit solidly during the memory test.

This morning I realised I had a power supply in another machine with the 4-pin 12v connector.

I've "borrowed" that and the startup has been 100% reliable. It's a better make, but only rated 250W.
However it does introduce a small number of errors on the digital TV card - though nowhere near as many as with the new "550W" supply. The thing those have in common is Passive PFC. The original "400W" unit does not seem to have PFC.

So, it would seem that the motherboard etc is OK and it's just a case of the brand of power supply that I got are just c-r-a-p.

I will just have to get a big-brand-name power supply that will work properly without causing interference to the digital TV card.

The actual manufacturer of the dodgy power supplies is not known, they are branded as "3XS" from Scan Computers, but have seen the same ones with different brand logos in various places.

Simon.

[grahamf]

Simon
Have you tried setting the BIOS settings to normal then restarting? Sometimes the motherboard tried to access the memory faster than it actually should, leading to some errors. Have you tried a different brand of memory? Can the motherboard take 2GB of RAM?
Graham

[SimonP]

I spoke too soon. It's just failed to re-start twice on this power supply.

Back to the drawing board, but it will have to wait. - I'm trying my new fan controller on the GD this afternoon.

Simon.

[SimonP]

Graham,
I haven't got any other compatible memory. This one needs dual channel DDR400 in a matched pair.
The nearest thing I have is ordinary DDR333.
Yes, it can take the 2GB.

I had already tried setting the BIOS to defaults - it seems to want to run 204MHz clock instead of 200, but even set at 200 I have the same problems.

I don't overclock any system unless I can afford to lose it.

Simon.

[shadow]

May be a bit of a long shot, but have you bought a new P4 and was the heat sink seperate? I managed to put the heatsink on incorectly on my second PC build, e.g. 6 oclock instead of 12 oclock. The heat paste wasn't contacting properly and was causing a very similar problem!

Did you wear an earth strap while handling the components? Any static can kill some delicate chips on the MB and cards.

Does it do this in safe mode too?

Good luck.

[shadow]

Did you do a reinstal of windows with a new MB? If not, have a look and see if you got a spare HDD and instal win onto it. swap the HD's over and see if that runs ok. As far as I'm aware a fresh install is a must with a new MB!