need bigger psu?
Home | Reviews and Features | Special Reports | Forums |

Results 1 to 5 of 5

Thread: need bigger psu?

  1. #1
    Join Date
    Jan 2001
    Posts
    105

    need bigger psu?

    I've got a duron 1300 w retail fan (no overclocking)
    abit kt7a raid mobo
    dvd-rom, cdrw and dvd-rw drive
    7200 rpm hard drive with drive bay cooler (2 mini fans)
    5400rpm hard drive off the raid controller (need to use a power
    splitter)

    running a generic 350w power supply now, no plans on upgrading or adding more devices to it (maybe a dvd-rom/cdrw combo drive when my dvd-rom dies) or a case fan or two

  2. #2
    Join Date
    Feb 1999
    Location
    Port Townsend, WA USA
    Posts
    2,784
    As long as you are booting ok and the system is stable then I see no need for a new PSU.

  3. #3
    Join Date
    Aug 2000
    Location
    Chesapeake, VA, USA
    Posts
    3,463
    If a cheap PSU is overloaded, it may work for a time, but it's a ticking time bomb and they often cause damage when they go. If it's a slow failure, you might have a few days warning to start load-shedding and getting a new one on order, but they just as often die in a cascade failure, with working rails spiking as other rails fail, and sometimes take down your mobo or components with it. If you can afford it, it's worth peace of mind to upgrade, but even an upgrade isn't a sure thing, as even the best PSUs can die randomly. But they generally do last a lot longer!

    In the end, it's basically a numbers/probability game... With a generic 350W PSU on your rig, you should most likely be OK. But it never hurts to upgrade!
    Pentium IV 2.4C Northwood- M0 stepping @ 3.2GHz HT
    Air Cooled w/ SP-94 heatpipe & 92mm Vantex Tornado at 45C
    4x256=1gb dual-channel 2-3-3-6 OCZ PC800DRAM @ 890MHz 3-4-4-8
    MSI Neo2-PLS w/I865PE & SATA @ 4x267=1068MHz
    BFG GeForceFX 5900@485/967MHz = 6284 3DMark2003s; dual-head 21" CRT & 19" LCD

  4. #4
    Join Date
    Mar 2000
    Location
    Auckland, New Zealand
    Posts
    2,331
    If a cheap PSU is overloaded, it may work for a time, but it's a ticking time bomb and they often cause damage when they go. If it's a slow failure, you might have a few days warning to start load-shedding and getting a new one on order, but they just as often die in a cascade failure, with working rails spiking as other rails fail, and sometimes take down your mobo or components with it. If you can afford it, it's worth peace of mind to upgrade, but even an upgrade isn't a sure thing, as even the best PSUs can die randomly. But they generally do last a lot longer!
    Not meaning to poke but I don't see how you could get spikes from a Switched mode power supply. There is a fixed switching frequency which chops up rectified mains. The outputs are achieved via transformer action, the input being the chopped up recitifed mains. Each winding is seperate with feedback winding keeping things in check. Only certain failure modes like primary winding shorts could cause higher secondary voltages.

    People here are forever talking abou slow faults and immenant PSU failure but it is rarely backed up with electrical/electronic proof - or even a picture.

    Generic PSUs do not deserve such a negative image.


    I will add if the switching FET fails as a collector-emmiter short you may see a primary voltage spike, this will be seen in proportion on the seconday outputs (your voltage rails) - that may be very bad.
    AMD Mobile 2500+
    A7N8X Deluxe rev2.0
    1GB Corsair XMS PC2700
    GeCube Radeon 9800 Pro
    Seagate SATA 80GB
    2xSegate 160GB in RAID0

  5. #5
    Join Date
    Aug 2000
    Location
    Chesapeake, VA, USA
    Posts
    3,463
    Who needs a diagram? Not like the generic transformers come with a troubleshooting diagram with which to prove their shortcomings... In fact, I'd be very surprised if all PSUs were switched; you can accomplish the same thing with a single 5-terminal unrectified transformer, someone will be selling a budget PSU with a single 5-terminal unrectified transformer. At any rate, a transformer with a heavy load that suddenly drops becomes a heavily charged inductor- which would almost instantly discharge upon any availible circuit as a voltage spike; that spike going back into the switching MOSFETs can overload and transfer a spike just as well as a wire would have.

    I'd expect high quality PSUs to have filtering and protections to prevent this from happening, but not all PSUs are created equal! There is a big difference between a $15 PSU and a $70 PSU and it's not just the quality of the fan.

    What I *do* know is that regardless of the electronics of the failure mode, PSUs that die run a disturbingly large chance of taking part of the computer with it when they go. This is reported on this forum time and time again. Whether that's from a voltage spike (seems the most likely cause) or from undervoltage problems or something else entirely is almost moot; cheap PSUs die early deaths and an early PSU death is a serious risk to the rest of the PC. Unless it's that failing components kill cheap PSUs, that could be it, too, and we've got it backwards, heh
    Last edited by grover; September 6th, 2004 at 02:08 PM.
    Pentium IV 2.4C Northwood- M0 stepping @ 3.2GHz HT
    Air Cooled w/ SP-94 heatpipe & 92mm Vantex Tornado at 45C
    4x256=1gb dual-channel 2-3-3-6 OCZ PC800DRAM @ 890MHz 3-4-4-8
    MSI Neo2-PLS w/I865PE & SATA @ 4x267=1068MHz
    BFG GeForceFX 5900@485/967MHz = 6284 3DMark2003s; dual-head 21" CRT & 19" LCD

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •