computer shut off followed by a burning smell

[Dalton Weaver]

while playing a game the game froze for a second them my computer shut off tried to restart. I saw part of my motherboards logo then it shut off again. So I reached down to try to turn it back on when I did so I smelled a burning smell I shut off the PSU and looked or any damage. I had just installed a new all in one CPU cooler so I was afraid it might have leaked it but it had not. The cooler has been working properly for about 3 days before this keeping temeture on my CPU in the 24-35° range at idle. After inspecting for damage I let it sit for an hour to see if it had over heated. When I tryed to turn it on again the light on the CPU pump will flash and the PSU will make a click noise but the system will power off right after that. I looked up other similar events and read that I should take out all of the unnecessary components. So I removed my GPU and one of my ram sticks and a wireless card that came with my motherbord. The same thing happens when I try to power it on. After taking out the components I looked at them for any black marks I can't find any on the back of my GPU and the ram looks good.

All of my components are about 4 months old
Components list:
8 gigs of g.skill Ripjaws memory
GTX 780 MSI gaming series
Corsair RM 750
i7 4770 K
Gigabyte GA -x97x-gaming g1 wifi- BK
liqtech 240

 

[A_Goat]

edit ;;;;;;;;; ;;

 

[Dalton Weaver]

they PSU is a Corsair RM 750 I listed all the components

 

[synphul]

Can you tell where the burning smell was coming from? Any chance you can get close enough to the back vent of the psu and see if the smell is stronger there? It doesn't sound promising that there was a burning smell (usually a power issue), followed by power instability and then odd clicking noises from the psu. Just going by those things alone, I'd be suspecting the psu for failure especially since you didn't see any signs of damage. The only other place I might have checked for burn or scorch marks might be the back of the motherboard, especially around the power connections - both the 24 pin mainboard and the 4/8 pin cpu power. That would require removing the motherboard out of the case though.

 

[Dalton Weaver]

The smell dissipated by the time I got to smell around all that was left was a metal smell and I could smell that more in the top of the case on the radiator fans the PSU did not really smell. from what I can see of the motherboard looks fine and the light on the power button of the motherboard will glow when the PSU is turned on but it will not post a debug code. the motherboard has two bios's so I tried to switch to the second but this did not cause the computer to start either.

 

[Dalton Weaver]

After tinkering around with it a little more I found that after the PSU makes that click noise pressing the power button only case or the motherboard will not try to start the computer. This leads me to believe that the power supply is broken and preventing itself from damaging the other components after I try to start it once. I'm not sure though so let me know that sound right.

 

[brispuss]

The RM750 PSU is suspected of being faulty. It is of average quality overall, but uses some lower grade components. So it is not surprising that it may be faulty.

If available, try another known working PSU on the system to confirm or eliminate the RM750 PSU as being faulty.

Regardless if the RM750 is faulty or not, it is recommended that this PSU be replaced with another better quality PSU such as -

Rosewill Capstone 750M
EVGA SuperNOVA 750 G2

 

[Dalton Weaver]

I cannot replace the PSU because I don't have another one is there any way I can test the current one. I know it's delivering some power because the motherboard power indicator is on and it will try to boot the system once when I first turn the PSU on.

 

[brispuss]

Testing procedure using a digital multimeter is here. Follow the instructions carefully! Please note that in the case of the RM750 PSU, the cables are all colored black. This means close attention to connector pin diagrams will be required to determine which wires are ground (negative), and which are positive.

Refer here for good pin out diagrams.

Basically the negative (black lead) probe of the multimeter goes to any ground wire/pin. The positive (red lead) multimeter probe goes to the positive wire/pin being measured.

That procedure will test outputs from the PSU while unloaded (not connected to components). The measured voltages should be very slightly higher than the nominal values of 12.00V, 5.00V, and 3.30V. If there is no voltage or if voltage WAY out of nominal values then the PSU is faulty.

 

[Dalton Weaver]

I removed the power supply unit from the case and the 24 pin connector leading to the motherboard to check its voltages. I looped the power supply on to the ground the fan on this model doesn't spin until the power supply gets hot so the fan does not start. upon first turning on the unit it makes the same clicking noise but when I turn it off it makes a slightly deeper sounding click noise and the fan moves a little bit. I checked all of the pens using a voltmeter and the very helpful pinout diagram. All of the voltages were very close to the voltages that should be this makes me think the PSU is OK so what can I test next.

 

[brispuss]

Did you check the voltages for the ATX_12V CPU connector (4+4 connector arrangement), the PCIe connectors (4 x 6+2 connector arrangement), and the SATA connectors?

If all voltages seem to be within tolerance, then the PSU is probably OK. However, this is not absolutely guaranteed as the PSU is not being loaded while taking these measurements. Sometimes when PSU's which appear to be fine when measured without load, may show faults when under load.

Reconnect the PSU.
Power up computer using the barest minimum of components.
Take voltage measurements using the digital multimeter of free connectors (PCIe and SATA connectors)
If voltages are about nominal then then PSU is almost certainly OK.

Try DIMM's one at a time in different slots. If there are still issues, try different DIMM's if available.

If there are still start up problems then the motherboard is now suspected of being faulty. There is no easy way of testing the motherboard other than by eliminating other possible sources of faults. Most likely the motherboard will have to be replaced.

 

[Dalton Weaver]

I began to test the rest of the leads with them all plugged in the voltages were reading right untill I started trying to check the little pins on the sata connector when checking that I herd another click from the PSU and it stopped reading any voltages. So then I put my computer in its minimal configuration to try to boot in the the bios I only plugged in the 24 and 8 connectors for my CPU but I left the PCI cord for my graphics card plugged in to the PSU to test voltages while the system was under load. With just the 24 and 8 pin plugged in I was getting no voltages out of the pci-e cord before I tried to start the system and the same after I tried to start it. So it seems to fail under the tinyest lode so should I try to get this unit replaced it should stil be under warranty and hope it won't happen again or should I buy one of the better ones you suggested?

 

[brispuss]

Definitely get a better quality PSU as suggested! They are far more reliable, and should last for years!

 

[Dalton Weaver]

so before I buy one its probably most likely the PSU right

 

[brispuss]

There are several possibilities here.

1) Going by the results of your tests it appears that the PSU is faulty.

2) It is possible that the motherboard only is faulty. The PSU may be seeing a short or overload and is activating it's protection and cutting out.

3) It is possible that both the PSU and motherboard are faulty. A faulty PSU might damage other components, so the motherboard may have been damaged by the faulty PSU.

Really the best way now to confirm whether the PSU or the motherboard is faulty/damaged is to try another known (quality) working PSU in the system. If there are still issues, then the motherboard is most likely faulty. If there are no further issues, then the original (Corsair) PSU is faulty.

It is suggested that the Corsair RM750 PSU be replaced anyway with a higher quality PSU as suggested previously, as the Corsair PSU is of low grade and is not entirely reliable. This replacement quality unit can also be used to confirm or eliminate the motherboard and/or the Corsair PSU as being faulty.