Minimum PSU for P4

dudlio
dudlio used Ask the Experts™
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I opened up my mom's Gateway P4 1.5Ghz the other day, just to take a look at it.  It's running on a 160W power supply.  I have never even *heard* of a 160W psu, but I looked up the model online and I don't see any indication that it's not what it says.  It's a Newton Power NPS-160CB.

My 1.2Ghz athlon, which is roughly the same speed, has already burned out a 300W psu.  Which is what one would expect.  Are P4's that much less power-hungry, or is this PSU lying?
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Commented:
If it's a Gateway and running with only a 160W PS I wouldn't want to add too much to it.  It apparently runs well with this low wattage although I have been throwing out PSUs that are less than 200W.
IT Project Manager
Commented:
Yes, there are 160W power supplies.  I've even seen 145W.  And yes, the P4's consume much less power than the Athlon.

Remember many of the large OEM's like gateway, dell, etc., don't think you'll be adding much to your system, and therefore don't feel the need for a higher-wattage power supply.  They also use them for space-saving considerations, especially in the sff (small form-factor) cases.  And, if they use features like onboard/integrated everything (video, audio, lan, etc.) they can save power that way as well.  Using lower power devices for these onboard solutions will also draw less power.

I wouldn't want to add a GeForce 4 Ti into it, with the power it requires, that's for sure . . .



Commented:
>>My 1.2Ghz athlon, which is roughly the same speed, has already burned out a 300W psu.

Yeh right!  You're operating on superstition and myth!

The Athlon 1.2GHz consumes a MAX of approx. 66 Watts of power.  Your 300Watt supply is capable of supplying FAR MORE than any Athlon CPU can ever need.  Most likey the rest of your system components don't even use another 66 Watts total so your system "power budget" is well below the 300Watt capacity of your supply.

The most likely scenario is that you purchased a CHEAP power supply and it burned out because it was poorly made!
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Commented:
jhance: I'm not certain that my athlon literally blew out the 300w power supply, but I am sure that it wouldn't even boot on a 250w.  So, 300W is not "far more" than I need but actually the bare minimum.  It was a cheap one too, I will give you that.
Glen A.IT Project Manager

Commented:
> jhance:

Nope, neither superstition nor myth.  Good old-fashioned science.

First, you have to understand the workings of power supplies and PC Components, and how much they really draw.  It's actually fairly easy to have a system that can use a full 300W or more, depending on your configuration.

There's good articles on the web that explain this better.  One you may be interested is at

http://www6.tomshardware.com/howto/20021021/powersupplies-02.html

Commented:
I fully understand the working of power supplies, power consumption, and the like.

The MYTH I'm referring to that the believe that there is something "magical" about 300W power supplies.

As long as the power supply is capable of supplying the power needs of the system, it doesn't matter how big it is.

Most systems today use far less than 300W.  But the only way to know for sure is to either calculate the requirements of the components or to actually measure the power consumption of the actual components.
Glen A.IT Project Manager

Commented:
Sorry jchance, I thought you were referring to my comments, not the power supply.

I think one of the biggest problems we run into today is unscrupulous manufacturers flogging power supplies as "300W" that arent necessarily up to the task of doing what is really required.  Cheap power supplies are just that, cheap.  A mercedes benz and a Kia both have four wheels -  but they do the job differently.  Power supply manufacturers seem to be the same.

AMD Recommends power supplies based on certain configurations:  Their "minimum" configuration that they consider is an Athlon cpu, 16Mb AGP Video, 128Mb RAM, 10/100 NIC, v.90 internal modem and 5400 rpm Hard Disk.  At this 'minimum' they recommend a minimum 250W unit.

When you upgrade these components, it can consume a lot more power.  IE:  a couple good 7200rpm HDD's can draw over 100W by themselves.  a 128Mb DDR-DIMM draws the equivalent of 30.  So if you add 2 hard drives, 2 DIMMS you're already at 160W theoretically . . .  That's without the CPU/Video even factored in, which by themselves can easily draw over 100 between the two of them.

I believe the overall determiniation in which power supply you need should be based on what you're going to do with it, and how much you're adding to the computer system.

If in the market keep in mind AMD still has a list of recommended power supply manufacturers on their site.

Other hardware sites review power supplies as well.  The moral of the story is don't buy a cheap one. . .  The Sparkle supply in my computer at home has two nice stickers on it:  One says "AMD Recommended" and the other "Intel Test Passed". (or something like that, don't remember the exact words).  They're half the reason I bought it.
Glen A.IT Project Manager

Commented:
Sorry jchance, I thought you were referring to my comments, not the power supply.

I think one of the biggest problems we run into today is unscrupulous manufacturers flogging power supplies as "300W" that arent necessarily up to the task of doing what is really required.  Cheap power supplies are just that, cheap.  A mercedes benz and a Kia both have four wheels -  but they do the job differently.  Power supply manufacturers seem to be the same.

AMD Recommends power supplies based on certain configurations:  Their "minimum" configuration that they consider is an Athlon cpu, 16Mb AGP Video, 128Mb RAM, 10/100 NIC, v.90 internal modem and 5400 rpm Hard Disk.  At this 'minimum' they recommend a minimum 250W unit.

When you upgrade these components, it can consume a lot more power.  IE:  a couple good 7200rpm HDD's can draw over 100W by themselves.  a 128Mb DDR-DIMM draws the equivalent of 30.  So if you add 2 hard drives, 2 DIMMS you're already at 160W theoretically . . .  That's without the CPU/Video even factored in, which by themselves can easily draw over 100 between the two of them.

I believe the overall determiniation in which power supply you need should be based on what you're going to do with it, and how much you're adding to the computer system.

If in the market keep in mind AMD still has a list of recommended power supply manufacturers on their site.

Other hardware sites review power supplies as well.  The moral of the story is don't buy a cheap one. . .  The Sparkle supply in my computer at home has two nice stickers on it:  One says "AMD Recommended" and the other "Intel Test Passed". (or something like that, don't remember the exact words).  They're half the reason I bought it.

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