Power Failure on PC

[crazy pyro]

I had a fault on my old motherboard which I hadn't got round to fixing for about 4 years (wouldn't post due to a motherboard timing error, tried clearing the CMOS and fitting a new battery but it still wouldn't work) so I replaced the motherboard. Everything worked smoothly for a week (I played a bit of Empire Total War so nothing particularly challenging for the computer), I fired up Destiny 2 and about an hour later the computer lost all power and refused to start up again.
I tested the power supply (a Corsair CS 650M which I had bought a touch over 5 years ago, hardly used due to the motherboard failure) using the method of shorting pins 4 and 5 on the motherboard connector as advised on the Corsair website. I could hear the sound of a relay switching but the fan didn't power up.
Concluding that the power supply was dead I purchased myself a Corsair RM650 power supply which I fitted this morning, PC still won't start up and when I do the pins 4 and 5 test I get the same symptoms as with the old PSU. Somewhat puzzlingly the light on the internal SD card reader connected to the USB header turns on when the PC is plugged in but not turned on with the new supply which suggests that it is transferring power to the computer.

Does anyone have any suggestions on how to get it working? I'd rather not have to return the PSU as a dead on arrival unit and it feels like there is something else strange going on here...

 

[Bill_Bright]

All ATX power supplies are required to supply +5V standby voltage to several points on the motherboard when the computer is turned off, but the PSU is still plugged into the wall (and if equipped, the PSU's master power switch on back is set to "On" or "1". That might have been the reason for the LED lit you saw.

While not 100% conclusive, you might want to get yourself a PSU Tester. I keep one in my tool bag in my truck for house calls. The advantage of this model is that it has a LCD readout of the voltages. With an actual voltage readout, you have a better chance of detecting a "failing" PSU, or one barely within the maximum allowed ±5% tolerances (at least with the tester’s small internal load) as specified by the ATX Form Factor standard.

Use the tester to test your PSU when it is not connected to the motherboard or any other device.

You might also want to pull the motherboard to make sure no foreign object or extra standoff is under the board. Note that cases are designed to support 1000s of different motherboards. So, it is common for cases to have more motherboard mounting points than boards have mounting holes. A common mistake by the less experienced and distracted pros alike is to insert one or more extra standoff in the case under the motherboard. Any extra standoff creates the potential for an electrical “short” in one or more circuits. The result ranges from "nothing" happening (everything works perfectly) to "intermittent” problems to "nothing" (as in nothing works at all ). So, you might want to verify you only inserted a standoff where there is a corresponding motherboard mounting hole.

 

[crazy pyro]

All ATX power supplies are required to supply +5V standby voltage to several points on the motherboard when the computer is turned off, but the PSU is still plugged into the wall (and if equipped, the PSU's master power switch on back is set to "On" or "1". That might have been the reason for the LED lit you saw.

While not 100% conclusive, you might want to get yourself a PSU Tester. I keep one in my tool bag in my truck for house calls. The advantage of this model is that it has a LCD readout of the voltages. With an actual voltage readout, you have a better chance of detecting a "failing" PSU, or one barely within the maximum allowed ±5% tolerances (at least with the tester’s small internal load) as specified by the ATX Form Factor standard.

Use the tester to test your PSU when it is not connected to the motherboard or any other device.

You might also want to pull the motherboard to make sure no foreign object or extra standoff is under the board. Note that cases are designed to support 1000s of different motherboards. So, it is common for cases to have more motherboard mounting points than boards have mounting holes. A common mistake by the less experienced and distracted pros alike is to insert one or more extra standoff in the case under the motherboard. Any extra standoff creates the potential for an electrical “short” in one or more circuits. The result ranges from "nothing" happening (everything works perfectly) to "intermittent” problems to "nothing" (as in nothing works at all ). So, you might want to verify you only inserted a standoff where there is a corresponding motherboard mounting hole.

Thanks Bill, I've spent a bit more time with it this afternoon and it seems that the old PSU will start up when disconnected from everything else. I tried the same test with the new one and it happily started up.
I have added cables back in and identified that it is completely happy starting up until I connect the PCI-E 6+2 cable to my graphics card. I haven't yet figured out how to fix it but definitely some progress.
I've checked behind the motherboard and the only standoffs which are installed are those which the motherboard is attached to via the earthed mounting points.

 

[Bill_Bright]

Well, it should be noted that Corsair's lower tier PSUs have not lived up to the reputation the Corsair name originally earned. This is because Corsair decided to change OEM suppliers on their budget lines and went with a lower quality design. With that supply being 5 years old, that could be it - even though hardly used. The RM series, BTW, is known to be of good quality and reliability.

 

[EsaT]

I have added cables back in and identified that it is completely happy starting up until I connect the PCI-E 6+2 cable to my graphics card.

You sure cable is correct for the PSU?
That sounds like there's possibly something shorted and protections prevent PSU from starting.
And wrong cable and shorted card are pretty much the only things capable to causing that.

 

[Bill_Bright]

Wrong cable or damaged cable are possibilities as are failing PSU rail. But the card works with the Corsair RM so the card is not shorted.

 

[crazy pyro]

Well, it should be noted that Corsair's lower tier PSUs have not lived up to the reputation the Corsair name originally earned. This is because Corsair decided to change OEM suppliers on their budget lines and went with a lower quality design. With that supply being 5 years old, that could be it - even though hardly used. The RM series, BTW, is known to be of good quality and reliability.

Sorry, just to clarify, I am not planing on putting the CS 650M back in. My plan is to use the new RM 650 so it's reassuring that my new PSU is a good quality design at least!
The card unfortunately doesn't work with the new power supply either.

You sure cable is correct for the PSU?
That sounds like there's possibly something shorted and protections prevent PSU from starting.
And wrong cable and shorted card are pretty much the only things capable to causing that.

The cable is the one which was included in the box with the RM 650 so I'm confident it's the correct cable for the PSU.
I've pulled the card out and couldn't see anything in the PCI-E slot or on the pins of the card suggesting that it had shorted there. Any suggestion of what to look for?

 

[Bill_Bright]

Sorry, just to clarify, I am not planing on putting the CS 650M back in. My plan is to use the new RM 650 so it's reassuring that my new PSU is a good quality design at least!
The card unfortunately doesn't work with the new power supply either.

Well, I understood you were going to stick with the RM 650. But I got myself confused with another problem I am helping on and thought the card worked with the second supply. Sorry for the confusion. Since it does not work with that PSU either, then that sure would suggest your card is bad.

It would be good if you could temporarily swap in a less powerful card (one that does not require an additional power connection) just to make sure the PCIe slot is good.

 

[FreedomEclipse]

Rip everything out and do a barebones build. You dont even need to put any ram or a graphics card in. Just place the board on some cardboard. plug the power supply in and trip motherboard pins to with some long nosed pliers or tweezers and see if theres any life. If its works then it should start making long beeping noises. Then you start to plug things in like some ram or a GPU and see if theres any change. Its just a way to diagnose if the board is bad though this isnt a completely bulletproof diagnosis. Even though it boots, the board still could be toast. Plugging things in slowly just helps eleminate what could the the faulty component.

Dont put all sticks of ram in all at once. Do it one at a time and power the machine on. You just need to see that it posts

 

[Caring1]

The cable is the one which was included in the box with the RM 650 so I'm confident it's the correct cable for the PSU.
I've pulled the card out and couldn't see anything in the PCI-E slot or on the pins of the card suggesting that it had shorted there. Any suggestion of what to look for?

Just make sure it is the cable with PCI-e on it, not the one for CPU power.

 

[crazy pyro]

Well, I understood you were going to stick with the RM 650. But I got myself confused with another problem I am helping on and thought the card worked with the second supply. Sorry for the confusion. Since it does not work with that PSU either, then that sure would suggest your card is bad.

It would be good if you could temporarily swap in a less powerful card (one that does not require an additional power connection) just to make sure the PCIe slot is good.

I haven't got a less powerful card lying round so it may be time for a new graphics card. I'll try and figure out a suitable replacement for it in the morning.

Just make sure it is the cable with PCI-e on it, not the one for CPU power.

I'm definitely using the PCI-E power cable, it's got PCI-E written on one side of the connectors (2 * 6+2 pin connectors on the cable), on the PSU end it specifies that the connectors are for PCI-E 6+2 and CPU.

 

[Bill_Bright]

I haven't got a less powerful card lying round so it may be time for a new graphics card.

I would just hate to see you spend good money on a new card only to find out the problem is the motherboard. Even if you could borrow another card from another computer, or trusting friend or relative, it would be worth it to try first.

 

[crazy pyro]

I would just hate to see you spend good money on a new card only to find out the problem is the motherboard. Even if you could borrow another card from another computer, or trusting friend or relative, it would be worth it to try first.

Unfortunately the UK is pretty much locked down at the moment so making a journey back home (about 200 miles) to borrow the graphics card from my Dad is a no go and as far as I am aware all of my local friends have laptops.
I have realised that the Core i5 3570K has its own integrated GPU so I have just fired up the computer using that for a display and it seems to be working so far with the HD 7850 removed so as long as the PCI-E socket isn't bust everything else in the system still appears to be OK.

I found a refurbished RX470 with a year's warranty on Ebay for £60 this morning so I have ordered that, it will give a bit of an upgrade in power over my previous card and seems to be about the cheapest way of replicating that level of performance at the moment from what I understand. Hopefully that solves the issue, I'll update the thread when I have installed and tested it.

 

[de.das.dude]

Are you doing the PSU test with it still connected to the motherboard in some parts? Then dont.
Please disconnect the PSU completely.
THat click you are hearing is the short circuit protection that is tripping up. Disconnect all the wires from the moterboard, and other hardware and try the PSU again. I doubt a corsair PSU will go bad in 6 years. I've been using mine for over 10 years or so.

 

[crazy pyro]

New GPU arrived on Tuesday, I installed the new card, and it seems to all work pretty smoothly now. Runs Destiny 2 at max settings without missing a beat.
Cost me a bit more to get the PC going again than I had expected (I was expecting £40 for the motherboard and wound up needing a new GPU, losing confidence in the PSU and was unable to get the Wi-Fi card to work so I replaced those as well), but it is now working again.

 

[xtreemchaos]

i had the same problem a few weeks ago i had a corsair cs750w and after about 30min playing a heavy VR game FO4VR the pc would hard boot, you could set the time by it bang on 30min so to cut a long story short i brought a new psu and everthing is good now, ive not give up on the cs750 im RMA it at the mo. the replacment psu i brought is seasonic gx focus 850w gold +. this is a well know problem with the cheaper corsair psu.

 

[Bill_Bright]

New GPU arrived on Tuesday, I installed the new card, and it seems to all work pretty smoothly now.

...losing confidence in the PSU and was unable to get the Wi-Fi card to work so I replaced those as well), but it is now working again.

Sorry it ended up costing more than planned but glad you got it going again. Thanks for coming back with your update!