pc power problem

Discussion in 'Computing and Networks' started by recca02, Sep 26, 2007.

  1. recca02

    Thread Starter Senior Member

    Apr 2, 2007
    well i have a few queries regarding power requirement of a computer.
    recently i fried my smps by accidently setting it for a low voltage and cap dielectric came out with a bang:(.
    so i was using a 300 watt one instead (previous one was 400w)

    here is what i want to know
    i recently monitored the power the ups was supplying the pc with a software provided by apc and it was around 160 watts.and that was with monitor plugged to ups hence my guess is cpu and speakers wud not probably be consuming more than 80 watts (correct me if i m wrong).
    but recently the pc started switching off quite frequently with some smell (typical of fried chips -i mean electric ones:D) i think this is due to overheating .the pc is not even able to reboot unless power is switched off.
    so is the power req of pc variable and did it cross 300watts? is it dependent on application? mind u the day wasnt really a hot one. or do u think something else is wrong here?

    edit: the 300w smps isnt a new one its somewhat old so possible heat sink problems.
    do u thik overheating of smps can turn off the pc?
  2. Eduard Munteanu

    Active Member

    Sep 1, 2007
    If the power supply cannot provide enough watts, then you can experience lockups and reboots. Yes, power consumption depends on what you're actually doing with your computer (that's why laptop batteries discharge faster when using certain apps).

    Your SMPS shouldn't overheat when more power is required, because it should have protection circuits. Of course, if the cooling isn't adequate, then such circuits are useless, since they expect the power supply to work okay at the rated power.

    Be aware that recent CPUs and graphic cards eat lots of power, so it's not that hard to go over specs. For example, see http://en.wikipedia.org/wiki/CPU_power_dissipation
    A 300W power supply is regarded quite weak nowadays (it may even be an overstatement, as I don't think many recent computers may run on such a supply).
  3. recca02

    Thread Starter Senior Member

    Apr 2, 2007
    yes, i should have thought about the laptop batteries,
    the gpu seems to be the culprit but still isnt 300 w gud enuf?
    so what say what must be the reason for the above incident do you think it was due to overheating of smps unit?
    or the processor or hard disk(if thats possible-it was quite hot itself though) or any thing else? -i doubt it was due to overheating of gpu since it has handled much more graphics than what i used yesterday.
  4. n9352527

    AAC Fanatic!

    Oct 14, 2005
    As well as the total power (300W), we should also consider the power capability for each voltage line. Most old SMPS have pretty beefy 5V and 3.3V lines, probably close to 220W. The rest are distributed to +12V, -12V and +5VSB. Modern ones have more power for +12V line, because of the 12Vaux lines for motherboard and graphic card. Not to mention multiple HDDs and optical drives.

    It might be of some benefit to make sure that the total power required at the +12V line does not exceed the SMPS rated power.
  5. recca02

    Thread Starter Senior Member

    Apr 2, 2007
    thanks Mr n9352527
    i had no idea about that maybe then i shud atleast put the old one for repair(or buy a new one) and see if that helps.
  6. Gadget

    Distinguished Member

    Jan 10, 2006
    Biggest thing with SMP PC power supplys is they dry up electrolytic caps. Cheapest option is probably just to replace the PSU, but in the case of those Odd specialist supplys..(older HP and compaq etc) then you should go through and replace all the electrolytic caps. Use 105 degree rated caps, and if Lo ESR caps have been used anywhere, be sure to use the same.
  7. recca02

    Thread Starter Senior Member

    Apr 2, 2007
    thanks Mr Gadget,
    that is something i suspected as well (not sure though)
    if so perhaps i will go for a new SMPS (its a real pain to find replacements here)