Random shut down, power led blinking and won't power on

Recently my pc's case rear fan is really loud when power on (it will reduce speed after 2 minutes), then 3 days ago I found the pc shut down by itself, though the power led was blinking green. I tried to press the power button to power up the pc but no response, it still was blinking green. I disconnected lots of cables include power cable, power switch connector then found the system will power on if I touch the power pin on motherboard with a screw driver. So I connected everything and it was working fine. I suspected it was caused by the case fan vibration so I disconnected it, thought it will be ok since I checked my cpu temp it was never too high.

Today I have the shut down twice again. The power led will blink (it will continue blink even if I disconnected the power cable for the PSU), pressing power button have no effect. It need some time to "cool down" before I can power up the system again. I read somewhere a hair dryer could speed up the process of discharge the residue energy but I haven't try this method yet.

I search around and think there could be several possible causes:
1. Power supply shut down for protection. I'm using a 400W PSU for AMD athlon II x4 640, 3 HDD. I checked PSU calculator again and found my configuration should only require 300W. I did use one cable from PSU to power the 3 HDD, so I split it into separate cables now.

2. Motherboard shut down for cpu overheating. Core temp said cpu 0 temp is 43 C, while HW info said the 4 cores have temp of 29C, TMPIN0 and TMPIN2 have 38 C 32C, and the HDD have 43C. I didn't do anything heavy in load when the 2 shutdown occurred today.

I ordered new case fan for rear and front (which is optional and not installed before in the case), will see what happens with the new fans.

3. I did reinstalled the cpu heatsink and fan after the first shutdown, and some thermal paste was lost in the procedure. I'm going to buy some more and apply it tomorrow.

What do you think? I'm going to try every method I found, but I'm not sure what's the real cause, and this random shutdown make me nervous for normal usage...

[update] it shut down again. And I can not power up the system now. If I wait some time and disconnect the power cable, the first attempt of powering on will make the fans rotate a little bit then stop, and the following attempts will have no response. I waited a longer time just found the first run will bring the fan to rotate a little bit more.

Is this the problem of psi?
6 answers Last reply Best Answer
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  1. Best answer
    1. Sounds like the PSU gave up its ghost to me. How old is it and what brand or type is it? Power supplies will constantly loose power over time, even more if they're of poor quality.

    2. The temperatures are OK.
  2. b0w said:
    1. Sounds like the PSU gave up its ghost to me. How old is it and what brand or type is it? Power supplies will constantly loose power over time, even more if they're of poor quality.

    2. The temperatures are OK.

    It's a 2 years old thermaltake tr2 500w. It is still in warranty but I'm hesitated to send it back because I could get just another refurbished one or even be rejected for "not proper usage" after spent $9 in shipping.

    I have a micro center nearby. Though the other models is not cheap. Which one do you recommend?

    Actually the one I bought is still on sale with same price

    I thought it was a name brand and was confident it was not the problem of psu, but after reading newegg reviews for coolermaster I guess every brand have some defective ones....
  3. Well, Thermaltake PSUs are of good quality, but they can die as everything else. Before you buy something, is it possible for you to borrow a PSU from someone, so you can be sure it's the matter of power. It can still be an other issue.
  4. Thanks for the response! I check the old psu with the method of connecting the power pin 16 of 24 pin connector with ground , the psu fan just moved a little bit. It seemed to be a psu problem. I bought another thermaltake 600 W psu and it worked. I was thinking buy a corsair one but it seemed all brands have defective units, just like you said.

    The 600W one is much lighter than the old 500W, and only the 24 pin connector is sleeved. I guess that's why it only cost a little bit more than the 500W.

    I will watch and see if the problem will appear again. Thanks for the help!
  5. Great! Watch it for a few days, if freezes will still occur, let me know.
  6. It has been 2 days and no problem. By the way, I exchanged the Thermaltake 600 W to Antec basiq VP450. The Thermaltake 600W is considerably weighted less than the old 500W, while the Antec basiq is more heavy.

    I also added a front fan to lower the Hard drive temperature.

    Thanks for the help!
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