20 pin power plug in a 24 pin M.B. plug

[lonewolf]

Hi all, My friend has a MS-7613 M.B. and the computer stopped working. (Won't turn on) So I said lets put a new power supply in. I looked up the board on the internet and it said 24 pin connector. I bought a power supply and took it over and when I opened up the case it did have a 24 pin connector but the power supply plug was only 20 pin. Is this right or did HP screw up building this. Could it have caused the MB to baff out?
I changed the power supply and it still won't turn on. If you hit the power button the fans twitch maybe 1/4 turn and nothing else happens. I checked the old power supply to see if it had the 4 pin plug that goes with the 20 pin and it didn't.
Thanks In Advance
Dave

[Midknyte]

It is possible to run a 24-pin motherboard with a 20-pin PSU.

http://www.smps.us/20-to-24pin-atx.html

The four pins that you are leaving open are just redundant pins for higher current capability

I'm assuming you remembered to plug in the 4-pin ATX12V in the socket by the CPU.

[lonewolf]

Yeah got the ATX12V.
Do you think the board is toast?

[Midknyte]

It's possible. Did you try reseating the ram as well?

I doubt a MB that new has bad caps, but it's something to check.
http://www.badcaps.net/

[jdc2000]

Post the make and model of the old power supply. Sometimes, when an el cheapo power supply fails, it can take out the motherboard as well.

[lonewolf]

Yeah reseated the RAM and unplugged all peripherals just in case. I have seen a bad CD-ROM stop a computer from booting up.
I didn't see any bad caps but sometimes they don't show.
Thanks
Dave

[lonewolf]

Bestec ATX-250-12Z Rev. D7R
Dave

[lonewolf]

I really think 250W is way to low for newer boards?

[Midknyte]

Bestec

Yikes. Those are some of the worst. 250W is pretty low nowadays.

[jdc2000]

Bestec - there is your answer. The motherboard is almost certainly fried. When Bestec power supplies fail, 99.9% of the time they take out the motherboard.

[lgbpop]

Bestec is OEM power for a lot of PC manufacturers, or used to be. Lord knows why unless it's the price. At any rate, before tossing the mobo try buying a real PSU with a 24- or 20+4 pin connector. While some 24-pin boards will run with only 20 pins connected I have seen plenty that will not do so.

P.S. I had to look at the date of this thread to make sure I wasn't necromancing. 20-pin PSUs are pretty old-school stuff now.

[lonewolf]

Thanks lgbpop, But as I stated at the beginning of the thread we tried a new PSU and it still didn't turn on.
Thanks
Dave

[SuperSparks]

Fried mobo

This is a good illustration of why I always urge people to pay the extra for a decent PSU when building a PC or replacing a power supply. Good quality ones still fail sometimes, but they do so gracefully. I've had 4 PSU failures over the last 11 years, but they were all good brands, and not one of those failures affected any other component.

[lgbpop]

Thanks lgbpop, But as I stated at the beginning of the thread we tried a new PSU and it still didn't turn on.
Thanks
Dave

Sorry, guess I misunderstood. I understood the post to say the new PSU you tried was a 20-pin connector plugged into a 24-pin header.