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DO I need a new PSU?

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tylerdurDAN

Technical User
May 21, 2005
6
US
I have a 250w PSU. I have a 120gb HD, floppy drive, cd-rw/DVD drive 6800 nVidia video card, 3.06 northwood CPU with hyperthread and 768 DDR400 ram. I have a micro-ATX motherboard that has a that has a 20 pin and a 4 pin connector to the motherboard.

Also can anyone tell me how much the 3.3v, 5v and 12v are supposed to fluctuate if at all?
my 3.3v is running at 3.2v
my 5v is running at 5v
my 12v is running at 11.52v

Should I get a larger PSU?
 
Judging from your hardware I would say yes, you indeed should have at least a 400W PSU. Your voltage will fluctuate, but slightly.

my opinion
xit
 
First, if you are measuring the voltages using the BIOS monitor, Speedfan, Motherboard Monitor (or similar utility)... they all depend on readings from your MOBO voltage sensors which are notorious for being inaccurate.

You should check the voltages at the 20 or 24 pin ATX connector using a digital multimeter (available from Radioshack, Home Depot, Lowes, Walmart, etc).

BTW... the voltages you posted above are fine if they were reported by a DMM.
 
Check the name plate on your current PSU for the output RMS not not peak.

Then use approx #'s for your load.

CPU(norwood) = 100 watts
HD = 10
Video = 25
fans = 2
mobo+ram = 10-15
CD/DVD = 5
other Periphs= 5 (rounded up) these include lan sound etc.

add 'em all up and compare to the RMS output and you should have a buffer of about 50% more does not hurt.

Hope This Helps



rvnguy
"I know everything..I just can't remember it all
 
Burning a DVD requires more power, so I'd agree that you can save yourself future problems by upgrading before you get into trouble.

-David
2006 Microsoft Most Valueable Professional (MVP)
2006 Dell Certified System Professional (CSP)
 
It is clear from rvnguy's figures that the 250watt is dangerously on the limit for this rig and given that his figures maybe on the reserved side ie:
The plain 6800 is nearer 40watts when working hard
And that there might be mutliple fans etc
This PC requires a safe 350watt or above PSU

Remember: not all power supplies are equal, take the output figures printed on a cheap unit with a pinch of salt!!! there is general consenses amongst professional users that QUALITY COUNTS! when it comes to power supplies, so don't go cheap, buy a quality branded replacement unit FROM:
Fortron Source, Channelwell Technology, Tagan, Antec, Enermax, Sparkle, Jeantech, Coolermaster, Zalman, Thermaltake, Hiper, Seasonic are all top shelf.

Martin

We like members to GIVE and not just TAKE.
Participate and help others.
 
Power (Watts) means nothing if you don't know the current---and not AC line current. 12VDC should NEVER be below 12 when reading from a meter. .5 volts is a bad flux. But if it is a software monitor, ...actually, 11.95 VDC is okay, but NO LESS!!!

The fact that your voltage is off really has nothing to do with how much power you need. Computer power supplies are equipped with voltage regulators (JFETS, MOSFETS), and they will keep voltage from fluctuating a lot. Not only does it sound like your psu is going bad, but a larger one indeed would be ideal. I have a P4 HT 3GHz, overclocked to 4%, 1gig 400MHz RAM, 3 SATA drives (two 100Gig RAID 0 and one 300Gig ), a DVD burner, video camera via firewire, and 4 fans---350 watt psu does just fine.
 
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