My PSU won't power my Mobo

[Mark R]

I'm in the process of trying to swap my BH6 for an NF7 - well, my current "300 W" PSU won't even power the Mobo.

That's a bare mobo - no RAM, no cards, no CPU.

Plug in the big 20 pin molex connector and the red power LED glows dimly. Power button does nothing. Manually starting the PSU by shorting the control pins, will turn on the green LED, but within a couple of seconds, the fans are slowing down, the LEDs start flickering and the PSU is making squealing noises.

Probing with a DMM reveals 2V on the +5Vsb line with the PSU in standby mode. And about 4V on +5 and 10V on +12 with the PSU operating.

I have no idea how this has powered, and still does, my lumbering 'Klamath' P2 - and will overclock it to 300 MHz as well.

Just in case you were wondering about the mobo - it's much happier connected to a new Enermax PSU. Unfortunately, I don't have a graphics card that will fit it - AGP slot seems to be back to front. And my new Radeon hasn't arrived from the shop (another long and woeful tale).

 

[eklass]

are you sure you've got the voltage setting on the back to 115V ?

 

[Mark R]

are you sure you've got the voltage setting on the back to 115V ?

Absolutely. It's set to 230V and taped there.

 

[bendixG15]

Short short ?????
Not logical, got to be something

 

[mechBgon]

Now, what video card is this that fits back-to-front? :Q I'm not liking the sound of that...

Also, if you plugged in any case USB-port wiring, unplug it for now.

 

[MrBond]

Originally posted by: mechBgon
Now, what video card is this that fits back-to-front? :Q I'm not liking the sound of that...

That seems weird. I've never seen that on a mobo before...

 

[Mark R]

I have a Matrox G200 AGP - I can assure you that there is no way that it will fit into the NF7's AGP slot. There is a cut-out in the card's edge connector about 1/3 of the way from the backplate. On the NF7 there is a key in the slot, which expects a cut-out about 1/3 of the way from the other end of the connector.

A Geforce2 GTS, however, does fit - it has 2 cutouts in the connector.

 

[TROGDORdBURNINATOR]

Sounds like a short to the case or something. Try it outside of the case.

 

[Mark R]

I assure you that it is not a short. I never installed it in the case - just tried it on some clean paper.

My point is just how bad some PSUs are - such the one I have. During use on my P2, the voltages fluctuate so wildly with CPU load that it interferes with the video timing. Every time CPU load changes the picture on the monitor jumps left or right about 2 or 3 pixels. Running Prime95 or similar keeps CPU load up, and prevents this effect.

Needless to say, the new PSU has completely cured the shaking picture.

 

[eklass]

Originally posted by: Mark R

are you sure you've got the voltage setting on the back to 115V ?

Absolutely. It's set to 230V and taped there.

... and you're in the U.S. ?

my psu sure as hell has 115 set.. and well, i'm typing now, aren't i?

if it's set (incorrectly) to 230V your comp will power on for about 1 second before it powers off

try switching it

edit: and if your enermax is set correctly, this is why it may work on your enermax and not on your other

 

[ScrapSilicon]

Originally posted by: mechBgon
Now, what video card is this that fits back-to-front? :Q I'm not liking the sound of that...

Also, if you plugged in any case USB-port wiring, unplug it for now.

has the new spec AGP slot ...1.5 cards only..I encountered that on a Shuttle mobo...no old Voodoo3 cards..

 

[mechBgon]

Originally posted by: Mark R
I have a Matrox G200 AGP - I can assure you that there is no way that it will fit into the NF7's AGP slot. There is a cut-out in the card's edge connector about 1/3 of the way from the backplate. On the NF7 there is a key in the slot, which expects a cut-out about 1/3 of the way from the other end of the connector.

A Geforce2 GTS, however, does fit - it has 2 cutouts in the connector.

I hope you didn't try to run it that way I see from your profile that you're in the UK, so I assume 230V is the norm there.