20-pin powersupply in 24-pin motherboard

[Vice93]

So I'm trying to help get my mothers computer working, but it doesn't seem to boot (no display to monitor, but fans start up).

I tried a bunch of different things but nothing seems to work. However when I looked at all the connections I found that the powersupply was connected to the motherboard using a 20-pin cable, whilst the motherboard had a 24-pin input.

The motherboard in question is FM2-A55M-E33.

So my question is; do I need to buy a new powersupply with 24-pin or a 24-20 pin converter, or won't this help me at all solving the issue?

Any help is appritiated.

 

[InvalidError]

The extra 3.3V and 5V pins were added back in the days where PCs were drawing tons of power from those rails. These days, practically all the power comes from the 12V rails and the CPU has its own dedicated ATX12V/EPS12, which makes it highly unlikely the extra main connector pins will make any difference.

You did not say what the PSU was but if it only has a 20-pins connector, I would guess it is fairly old or has very low ratings. In that case, you could simply have a dead but still sort-of-working PSU. If it was a low quality PSU, there is also the possibility that it fried the motherboard.

 

[Vice93]

You did not say what the PSU was but if it only has a 20-pins connector

Yeah I didn't say what the PSU was because frankly I don't know. It's about 7-9 years old and the reason I asked was because I thougth this might be the issue. I'll get my mom to buy a new one.

 

[Vice93]

I just tried to start the PC using my own power supply (connected the 24 pin and 4 pin next to CPU) however this didn't work either. So what do you suggest I do now? If the motherboard is fried as you say, I'd need to buy that one new as well.

I didn't say this earlier, but all components except the PSU are brand new.

 

[InvalidError]

If you do not have a "PC Speaker" connected to the motherboard's speaker header, you might want to try that and see if the computer is putting out beep codes when you try powering it up. Some motherboards have a piezo speaker directly on-board. If you get absolutely nothing out of that then your computer is failing to start running its BIOS self-test. Either you forgot to connect something (like the ATX12V cable) or you your motherboard/CPU are not working for some reason. You should be able to at least get the initial turn-on beep if the CPU starts running the BIOS code.

 

[Vice93]

If you do not have a "PC Speaker" connected to the motherboard's speaker header, you might want to try that and see if the computer is putting out beep codes when you try powering it up. Some motherboards have a piezo speaker directly on-board. If you get absolutely nothing out of that then your computer is failing to start running its BIOS self-test. Either you forgot to connect something (like the ATX12V cable) or you your motherboard/CPU are not working for some reason. You should be able to at least get the initial turn-on beep if the CPU starts running the BIOS code.

Just tried that, there is no beeping sound from my speakers, nor the motherboard itself.

 

[InvalidError]

Just tried that, there is no beeping sound from my speakers, nor the motherboard itself.

The "PC Speaker" is a four-position header the "case speaker" would normally connect to but most modern case do not have one. It has absolutely nothing to do with the integrated or add-on sound chip.

Unless you have a speaker connected to that header or have a motherboard with built-in speaker, you will not hear the BIOS's POST beeps... which is a curse while troubleshooting but a blessing the rest of the time.

 

[Vice93]

Just tried that, there is no beeping sound from my speakers, nor the motherboard itself.

The "PC Speaker" is a four-position header the "case speaker" would normally connect to but most modern case do not have one. It has absolutely nothing to do with the integrated or add-on sound chip.

Unless you have a speaker connected to that header or have a motherboard with built-in speaker, you will not hear the BIOS's POST beeps... which is a curse while troubleshooting but a blessing the rest of the time.

So what do you propose I do seeing as I don't have a speaker like that available. Should I go ahead and buy a new PSU and motherboard to see if that works?

 

[InvalidError]

You can probably buy a PC-speaker for something like $1 at the nearest flea market. I would try that to see if the motherboard has anything to say before throwing parts at the problem.

If you have a multimeter, you should check all your voltages including 5VSB for anything obviously out of spec.