Power Supply and the AMD 64

Posted on 2004-11-27
Last Modified: 2010-04-26
I have just bought a knew AMD 64 CPU with a motherboard made by SMI. I have learned that the 12v rail needs to be above 20A.

Currently it seems that my board is not getting enough juice. I have unplugged everything, but it seems nothing will work save the CPU fan and motherboard lights.

I did ram tests and so on. Nothing happend that would indicate any mother board or anything attached to it would be causing the problem.

I took out the Power spupply and saw that my 12v rail is only putting out 12A.

5v putting out 30A.

3.3V putting out 14A.

I did research and from the AMD website have determined my power supply is not powerful enough. My friend purchased the Antec power supply and solved his power supply issues earlier.

My question is that is this the right conclusion about replacing the power supply before i blast money on it?

This would not be urgent if it was not the computer I use for college and research.
Question by:gmar777
    LVL 8

    Accepted Solution

    12 amps is on te low side, but it depends how many other 12 volt users you have.

    Do you have a MOLEX powered GFX ?

    How many drives and fans ?

    Do your Motherboard require the additional ATX12v (4 pin square) connector and have you plugged it in ?
    Perhaps your PSU does not have the additional ATX 12v connector ?

    If the answer to the 2 last questions is YES ,you need to buy a new PSU ?

    LVL 8

    Expert Comment

    Can you provide additional information about your Motherboard

    You are sure its not MSI(Micro Star International) instead of SMI

    LVL 4

    Expert Comment

    The ideal powersupplies are usually about 450w output and normally gives about 20-22A depending on the brand.
    For instance, Vantec has some powerful and costefficient solutions.
    I'd suggest that you spend about $50-100 on a new powersupply which also allows you for upgrades and additional cooling if needed.

    Author Comment

    OK update your right it was a MSI heh. It does have the extra 4 pins on the side. is that a special power supply?

    I have an FX video card. 3 case fans and latest sound blaster. 80 gig western digital HD.
    LVL 8

    Expert Comment

    Do your Motherboard require the additional ATX12v (4 pin square) connector and have you plugged it in ?
    Perhaps your PSU does not have the additional ATX 12v connector ?

    If you dont have the ATX12v connector on the PSU you need another compatible one as this connector is feeding the CPU
    Good brands are fortron & enermax

    Its alot of difference if its a gf 5200 or 5950 ultra ?

    LVL 13

    Expert Comment

    gmar777, what is the modle number and revision number of the Motherbaord, it is usually printed on the up side of the board itself, and sometimes on the box it came in, but sometimes the box will not give you a revision number.

    One thing about most PC stores, you can return or exchange the Power Supply if it isn't right, but the PSU box should give you all the info you need.  If you can, get the TruePower model, the Antec True430 seems to be compatible:

    ATX Form Factor, ATX12V compliant for Pentium 4 (backward compatible with previous Pentium versions) and AMD systems, but they are a bit high priced @ $99.00 USD.

    And StarTech has a 400 Watt PSU for $41.00 at CompUSA: cheaper if you  go to

    CompUSA: has a Rosewill PSU

    Type: ATX
    Maximum Power: 500W
    Hold-up Time: > 16ms at Full Load and nominal input voltage
    Efficiency: 70% min. under max. range load
    Over Voltage Protection: +3.3V +5V +12V
    Input Voltage: 100-120 vrms or 200-240 vrms switch-selectable
    Input Frequency Range: 47-63 Hz
    Input Current: 10A/5.5A
    Output: +3.3V@30A, +5V@45A, +12V@26A, -5V@0.5A, -12V@1A, +5VSB@2.5A
    MTBF: 100k hours at max. load, normal line and 25°C
    Approvals: CSA, CB, TUV, FCC, UL
    Features: Black Chrome Mirror Finish, Fan Speed Control Switch (low, auto, and high)

    Cost: $44.95 as you can see, the 12v is at 26amps should  be more than enough.

    Author Comment

    OK great news i got things working from buying a antec 400 watt power supply. HOwever, the power to my video cards fan is not functioning. Is this lack of power or is something missing? The video card has a fan and the power connector plugs into the video card itself. Any way i can get that working?

    If the fan is needed I do not want to fry it.

    It is a 128mb nvidia 5200 fx.

    The video card seems to be working fine just the fan not working has me paranoid.

    Author Comment

    Never mind i have a big enough heatsink on my 5200 and seems the fan hasent been working any ways after my tests. Also the 5200 dosent require a fan supposively the company that created mine did it for looks more than need. Thanks all for help! Now its just wresteling with my software setup.

    Problem solved!

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