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Asus Pc power supply

Hi there. I have an ASus desktop (which runs my cctv network).

This died about 2 weeks ago and it seemed that the power supply unit was the problem. It was a standard n Asus 4s-435 which is a 350w unit i believe.

As it was a 'hurry job' I purchased a stanard 650w power unit the same size and installed it assuming 650w was plenty spare and would not cause any problems.

However the PC now boots up for about a minute , showing the screen and then shuts down again continually.

Am i being stupid? is this because of the oversized power unit 650 vs 350w, or something else?

any help appreciated.


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  • 5 more comments 
  • tobes
    tobes Jan 07, 2009

    hi there, sorry i'm a bit new to this.

    Nope, no death screen, boot up screen started as normal except it was offering to start in safe mode and then it started to open X start screen and then machine died .

    it does this continually as i get no more than 1minute max of power as it is booting up. I'm assuming power supply is not at fault (!) as it is brand new.


  • tobes
    tobes Jan 07, 2009

    hi there, sorry i'm a bit new to this.

    Nope, no death screen, boot up screen started as normal except it was offering to start in safe mode and then it started to open X start screen and then machine died .

    it does this continually as i get no more than 1minute max of power as it is booting up. I'm assuming power supply is not at fault (!) as it is brand new.


  • tobes
    tobes Jan 07, 2009

    oops, this to wraiith303, I thinnk i send a reply to the wrong space.

    I'll try that out, as i had cleaned/dusted the inside and the CPU fan when installing this new power supply. Does it heat up that quick?

    Also , just to clarify , it does not try to reboot on it's own, but i have to physically press the 'on' button again.


  • tobes
    tobes Jan 07, 2009

    Er hi again..rats nope. no access to PSU tester unless i go back the shop..

    I presume if i had it completely out of the machine and not connected to anything, and then plugged in the power cable and switched on it, if it is ok it should just start up the fan and hum away quite happiliy ?? or am i being naive ?

    Eg it will demonstrate it is working fine as a stand alone unit. Hence the problem is likely to be either the CPU cooling fan as per your point or some weird wrong wiring issue (eg me?)

  • tobes
    tobes Jan 08, 2009

    Aloha Wraiith303 you star,

    Well some progress.., as you suggested I removed the heatsink CPU fan and cleaned it again. As i had no thermal paste with me i just refastened it very carefully and securely to the CPU and tried pressing the 'on' button.

    It booted up ok and went on working through WIN XP start and even showed me some of the CCTV app working.. Then.. it stopped dead again and turned off...sob..

    I have to wait about 3 minutes before the on/off button does anything, then it does the same thing after 3-4 minutes running.

    i'd hazard a guess this is an overheating problem, as you indicated, probably on the CPU. Will a generous application of thermal paste fix this? I've not used this stuff before and is there anything else i should look for?

    thanks again

    tob .

  • tobes
    tobes Jan 08, 2009

    Ahem , well i burnt my finger touching the CPU immediately after i removed the fan, so now i've learnt. ouch ouch ouch...take it to a ?never. i'll get some paste and try it again..'If at first you don't succeed, ..keep going til you wreck it' as my now dead dad used to say (. he was a bomb disposal

    Anyway thanks again. if you are ever in London lemme know.


  • Curtis Tuendemann May 11, 2010

    Are you receiving a "Blue Screen of Death"?



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  • 39 Answers

Sounds like heating problems. what i'd recommend is to go buy some thermal paste, remove your heatsink/cpu fan. wipe the bottom of the heatsink clean with a cloth, and do the sam with the top of the cpu. now apply the thermal paste (about 3mm cubic or whatever the packaging says) to the centre of the cpu, and secure the heatsink/fan onto the cpu. make sure your heatsink is on your cpu SECURELY. In my experience a pc that boots up, works a while then reboots out of it's own is having heat problems. especially if the pc wont boot/reboots quickly after the initial reboot.

Posted on Jan 07, 2009

  • Beeuwen Gerryts
    Beeuwen Gerryts Jan 07, 2009

    So it shuts down instead of rebooting? In that case it can still be heat, depending on the motherboard type and the safety measures in place. Otherwise it COULD be a faulty PSU. Its rare, but the do sometimes arrive faulty out of he box. Do you have access to a PSU tester? or a PC repair shop who is willing to test it for you?

  • Beeuwen Gerryts
    Beeuwen Gerryts Jan 08, 2009

    WOAH! You ran he CPU without thermal paste?! That was very brave... lol.

    Yeah, i believe thermal paste ought to solve your problem. They go for about R57 retail here, so i guess... roughly $5 for a tube. Also, you'd only be using very little of it. It might be cheaper to take into a shop and let them do it... Up to you! :)

    As for the power supply, no if you just plug it in, it won't start up. Also, even if it starts up you know that the damage isn't severe, but it could still be damaged. As for the wiring issue, i doubt you are at fault. It's rather difficult to wire a pc wrong (from the PSU atleast)



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