Power supply needs help

[mcseguy9]

Hey guys, I've figured out my power consumption needs from this site:

http://www.firingsquad.com/guides/power_supply/default.asp (Choosing the right power supply)

From this article I've figured out that my wife's PC's power supply needs on each rail are as follows:

3.3v rail - 6amps; 5v rail - 15 amps; 12v rail - 6 amps.

I've started looking at power supplies at newegg.com and it honestly looks like the cheapest one they have will supply her setup with all of the power it needs to each rail. Here are her specs:

Athlon XP 2000+ CPU
Mobo w/integrated devices
3 fans
512MB DDR RAM
AGP Graphics card
2 IDE drives
CD-RW
Floppy drive
Keyboard
Mouse
USB thumb drive

Using that site I added up the estimated current consumption going over each rail and those are the figures I came to (rounding up).

If you go to this page:

Hey guys, I've figured out my power consumption needs from this site:

http://www.firingsquad.com/guides/power_supply/default.asp (Choosing the right power supply)

From this article I've figured out that my wife's PC's power supply needs on each rail are as follows:

3.3v rail - 6amps; 5v rail - 15 amps; 12v rail - 6 amps.

I've started looking at power supplies at newegg.com and it honestly looks like the cheapest one they have will supply her setup with all of the power it needs to each rail. Here are her specs:

Athlon XP 2000+ CPU
Mobo w/integrated devices
3 fans
512MB DDR RAM
AGP Graphics card
2 IDE drives
CD-RW
Floppy drive
Keyboard
Mouse
USB thumb drive

Using that site I added up the estimated current consumption going over each rail and those are the figures I came to (rounding up).

If you go to this page:

http://www.newegg.com/app/ViewProduct.asp?DEPA=1&order=STOCK&submit=property&catalog=58&mfrcode=0&propertycodevalue=3175,%200,%200,%200,%200,%200&keywords=&minprice=&maxprice=&description=+&Order=price

You can see that the first power supply meets my needs, at least from the estimated current consumption perspective. I know the cheapest power supply isn't necessarily going to last long, but I want to make sure that I'm not going crazy and that these figures and what I've found are correct. Maybe I'm missing something, as the first power supply is only a 250W power supply. Any help would be great.

[lptech]

mcseguy9-

I think that you need to re-evaluate your power needs carefully. 250-watts is just asking for big trouble unless you like trying to guess where your anomalies are coming from. Remember skimping on the PSU (Power Supply Unit) can end up costing you in the long when it decides to fail and take along the components that are attached to it! Are you really willing to risk destroying all of the components attached to it? I know for fact that underpowered system have a higher rate of total failure then ones that have more than adequate power available.

I see many failed PSUs and other components on a daily basis at work and it all comes down to having the PSUs overtaxed beyond their capacity and the failure rates for the items attached to them are quite scary to tell you the truth. Working for a company that supplies replacement parts for HP/Compaq and Dell makes me kind of more knowledgeable than most people since I write up reports on the causes of failure on these components!

A good rule of thumb is to multiply the figure you came up with by about a factor of 1.8 times and that should be the actually power rating of the PSU that you should use! Don't forget that during startup (POST) all of the components draw power on all of the rails, i.e.-motherboards, HDD(s), FDD, memory modules, etc. and if you are running at maximum capacity at that time, you will be subjecting the components to unstable power which shortens the life of the components alot sooner than you think if your PSU is running beyond the full capacity of its power rating.

I would suggest looking at the following link for it is more reliable and accurate in my opinion.

http://www.pcpowercooling.com/maxpc/index_cases.htm

Add up what each component uses and then multiply by a factor of 1.8 times to get at the correct recommended power rating for your power supply unit. Hope that it helps you in your decision making. Good luck!

LPTECH

[ukulele]

Well you figured the load, now add some extra headroom (at least another 25%) and it should be fine.

[mcseguy9]

Thanks for the help, guys. I will look into better manufacturer's and higher wattage, all the while making sure the rails amps are more than enough.

[fishybawb]

Give this one a look:

http://www.newegg.com/app/ViewProductDesc.asp?description=17-104-979&depa=0

[Bat25]

Originally posted by fishybawb
Give this one a look:

http://www.newegg.com/app/ViewProductDesc.asp?description=17-104-979&depa=0

Right on. The fortron actually has better peak power and better rails than most 400-450 watters. The fortron 350 would be perfect. Enlight 360 or 420 would also be good.