Trouble with the PSU/motherboard connection

[Titan457]

This is my first time building a computer and I've been having an issue with making a complete circuit with the PSU, morherboard, and CPU. Whenever I try to hook everything up, the PSU fan doesn't turn on. I know that the PSU works, and the CPU and motherboard have both been replaced at least once. I've asked a few people and they don't know what to do.

Any ideas as to what's wrong and/or how to fix it?

 

[Multipack]

The PSU fan may have a zero RPM mode for low load, Depends on model. Only the very top end ones do though.

How do you know the PSU works? Have you tried the paperclip test for signs of life?

 

[Titan457]

Sorry, I didn't mean to downvote your answer.

There was a testing dongle that came with the PSU and that shows that it works. I also plugged it into other components and they were powered.

 

[Multipack]

So, when you connect it all up what happens? No life at all? Are you certain you are connecting all power cables properly? Including both motherboard power supplies? When you say plugged other components in what do you mean? The motherboard determines whether other components fire up. They wont do it without it.

What parts do you have?

 

[tsnor]

"..There was a testing dongle that came with the PSU and that shows that it works. I also plugged it into other components and they were powered." So the PSU fan came on in these cases, but not with the MB power cables attached?

IF so, then pull all parts from the MB except the CPU, CPU fan, PSU. No disk cables, no fan cables, no USB2, USB3, etc. all wires off the MB except the two power cables from the PSU. Now start it. If you get a "no memory" error and the PSU fan works great. If the PSU fan does not work then one of the following is happening
1. The MB is shorting against the case. Check mounting hardware. Try removing MB and repeating test on a piece of cardboard like the MBbox.
2. The MB power wires are pinched and shorting
3. The MB has failed and is shorting
4. The PSU is bad, but in this case from your other test it's likely not the PSU
5. The CPU is bad, but again not likely
6. The CPU fan is shorting. Not likely.
7. You've plugged the 4 pin conenctor in BACKWARDS. It sounds unlikely, but I 've seen it. You can shove the connector in the wrong way.

If you do get the "no memory" error code with the PSU fan working, then unplug, add some parts back in and then start up again. Eventually you will find the part that is shorting or you will find that all the parts now work.

Update: forgot to add, once you have all the case headers off the PC there is no switch to start your PC. A few high end MBs have a button for this. The rest of us use a screwdriver to momentarily short the power button pins simulating pressing the button. You only hold the screwdriver on for a second or less. The MB detects the short between the pins and starts its power on self test. You can see videos of people doing this on youtube.

While I'm updating this post, the "no post, no video" sticky in this forum has a description of "bread-boarding" and some other things to check. It's worth reading. http://www.tomshardware.com/forum/261145-31-perform-steps-posting-post-boot-video-problems

 

[Titan457]

Yes, the PSU fan is working in those other cases, and there is no "no memory" warning. I am breadboarding, so the issue isn't it shorting with the case. As mentioned in the original query, I've replace do both the mobo and the CPU multiple times and im still getting the same issues. I haven't tried to short the mobo yet, but I'll update when I do.

Thanks for your advice.

 

[tsnor]

Yes, the PSU fan is working in those other cases, and there is no "no memory" warning. I am breadboarding, so the issue isn't it shorting with the case. As mentioned in the original query, I've replace do both the mobo and the CPU multiple times and im still getting the same issues. I haven't tried to short the mobo yet, but I'll update when I do.

Thanks for your advice.

If you breadboarded with the only wires corrected to the MB being the power cables, and the only parts on the MB being the CPU and the CPU fan and the board doesn't post with a no-memory code then you know:
1. You failed to plug in both the 24-pin and 4-pin power leads. Unlikely, but check again they are in good at both the MB and (if modular) at the PSU.
2. The MB is dead
3. The PSU is dead
4. The CPU is dead.

Note a bad PSU can kill a MB, so this is not as simple as replace them one at a time.
I would swap in any old PSU you have lying around to see if you can get life from the MB.

If you did the breadboarding with things like the disk cables or case header plugged in then you need to do this again with just the bare MB to rule out things like USB ports shorting. I saw a totally dead laptop come back to life when a mini-pci network card was removed... and continue working with the exact same network card reinstalled - just must have got dirt shorting something in the mini-pci port the first time.

Good Luck.

 

[grunion]

Hi,
I have been trying to help Titan with this build and it really has us stumped. We purchased a package from Newegg with ASUS H110M-E motherboard, EVGA 450 PSU, Intel i5 CPU, GEForce 1050, Hyper212 cooler 8gb DDR4 and InWin gaming case. New out of the box we tried just breadboarding before installing anything in case. We took ESD precautions, plugged PSU, CPU, beep speaker and just stock fan into MB and no apparent response. Not knowing what response to expect we plugged video card and monitor in but no signal going to monitor. We tried with Hypercooler and set all components/cables up in case and still no response when power on PSU turned on. When we plug dongle in to 24-pin connector of PSU the fan does go on.
We called ASUS support and they suggested return MB for replacement. 10 days later replacement arrives and same story. ASUS now recommended we replace CPU. 10 days later CPU arrives and still same story.

Here is a link to some photos in case you might notice something obvious that we are overlooking. Kind thanks for any ideas.

https://imgur.com/gallery/KtD3x

 

[Titan457]

I don't have any spare PSUs, so I don't have any way to test that. It sounds like the only other answer is that there's is a faulty component, but I think it's unlikely that I would get multiple different broken parts. I might as well try to replace them anyway.

Am I interpreting your answer correctly?

 

[tsnor]

I don't have any spare PSUs, so I don't have any way to test that. It sounds like the only other answer is that there's is a faulty component, but I think it's unlikely that I would get multiple different broken parts. I might as well try to replace them anyway.

Am I interpreting your answer correctly?

YES! and if you had it fail with old MB and new, old CPU and new the last component is the PSU.

Do you have a working PC nearby. You can actually pull the MB conenctors off the MB in teh working PC and plug them into the MB. Lean the MB up against the case of the working PC so the cables reach and nothing is shorting. The MB should beep no memory.

To confirm, with just the MB, CPU, CPU fan and power supply, nothing else attached when you attempt to power up the MB the fan on the power supply does not spin and nothing happens. If you unplug the MB, plug in the test dongle then the PSU fan spins right up. .... Something is shorting somewhere.

 

[Multipack]

At that point the only real thing it can be is the PSU, or one of the cables. Try the paperclip test on the PSU, and if you cant RMA it and dont want to buy a new one yet then invest in a voltmeter instead.. https://www.lifewire.com/how-to-manually-test-a-power-supply-with-a-multimeter-2626158

Also make sure both 4 pin and 24 pin are firmly connected to the board. They need a little pressure sometimes to clip in properly.