Why is a good Power Supply important?

[ahleung]

I'm running a xp2600+ with 2 sticks 512mb pc2700 ram and 2 u160 scsi harddrives, geforce ti200, why would I want a 400w over a 300w power supply?

 

[vicks]

Read this: Choosing the Right Power Supply

Thank me later.

 

[Lord Evermore]

You don't necessarily. Good power is important because a cheap power supply may not provide a consistent level of current. For instance during bootup, all devices in the system start pulling the maximum amount of power (an average IDE hard drive can pull 25W on the 12V rail and 2 to 5W on the 5V rail during spinup). During normal operation they use a lot less. Your PSU may be able to handle normal operation, but with all the voltage rails having a lot of current draw during bootup, it may not be able to supply them all well enough. If the supply drops too low, the system won't boot. Also, a bad PSU can't provide clean and steady power during operation, so the current may go up and down too much, which can cause damage to components as well as data loss.

400W isn't necessarily better than 300W. There are plenty of 400W and even 500W PSUs that don't supply as much power as a good brand 300W. Most important in modern systems is the +12V rail. This is the voltage used by the CPU, and a P4 board has a dedicated connected for that voltage in order to guarantee a good flow. Cheap PSUs may have a high total wattage, but the maximum sustained draw may be considerably lower. They also show very high current ratings for the 3.3V and 5V rails, but the 12V rail is skimped on because it's cheaper to do it that way.

Read through the forums, Cases and Cooling and General Hardware in particular, and search older posts. There are quite often threads about power supplies, with recommendations based on experience. In general, certain brands such as Antec and Enermax are very respected, but may also have their own drawbacks based on your needs and budget.

 

[AEB]

great article vicks i did not know all of that, i bought a generic PS and my dual p3's systems started rebooting abnormally maybe this explains why!

 

[garaget]

Originally posted by: Lord Evermore
You don't necessarily. Good power is important because a cheap power supply may not provide a consistent level of current. For instance during bootup, all devices in the system start pulling the maximum amount of power (an average IDE hard drive can pull 25W on the 12V rail and 2 to 5W on the 5V rail during spinup). During normal operation they use a lot less. Your PSU may be able to handle normal operation, but with all the voltage rails having a lot of current draw during bootup, it may not be able to supply them all well enough. If the supply drops too low, the system won't boot. Also, a bad PSU can't provide clean and steady power during operation, so the current may go up and down too much, which can cause damage to components as well as data loss.

400W isn't necessarily better than 300W. There are plenty of 400W and even 500W PSUs that don't supply as much power as a good brand 300W. Most important in modern systems is the +12V rail. This is the voltage used by the CPU, and a P4 board has a dedicated connected for that voltage in order to guarantee a good flow. Cheap PSUs may have a high total wattage, but the maximum sustained draw may be considerably lower. They also show very high current ratings for the 3.3V and 5V rails, but the 12V rail is skimped on because it's cheaper to do it that way.

Read through the forums, Cases and Cooling and General Hardware in particular, and search older posts. There are quite often threads about power supplies, with recommendations based on experience. In general, certain brands such as Antec and Enermax are very respected, but may also have their own drawbacks based on your needs and budget.

Exactly, I use a $45 300W psu on my xp2500 (@2.1) 1gig of corsair, dvdr drive, cdr drive, 2 80gig hds and I am smitten as a kitten. GG consumer power supply marketing again.

Just like how newer is not always better, you would say more wattage is not always better - if it isn't actual quality output in terms of 3.3v, 5v, 12v.