Newbie PSU questions

[Total Immortal]

How does one go about determining the correct size power supply for a given computer configuration? I've been poking around at newegg, and I notice that PSU's range from 150w to 660w, with just about everything inbetween. How do you know which size to use? And what's the consensus on PSU's that come with cases? Are they bad news?

 

[ekÆsine]

this will sound a bit dumb, but my rule of thumb is look at the price. example: a case with a bundled 500watt power supply for $50, a very bad deal. many people think just having at least 400 watts is good enough, that is a wrong assumption.

there is a online calculator that someone always mentions. i do not think it actually works though. here is another example of my method of estimating:

example: you have a p4 3.2Ghz or amd 3200 with 2cd-rom, 2or3 HDD,floppy,3 case fans, ect. this costed you $1500, a pretty expensive rig. i would get one of the most expensive PSU i could find. something like an antec truepower 550watt. see how my crazy rule of thumb works?

 

[Shrapnill]

Not bad really. I would agree more to that than with that stupid (VERY outdated) calculator people always post.

If you list the specs youll be running (anything that requires power including fans or CCs or anything) we could recommend a wattage.

as an example, I run a high spec PC (3200+, 3 HDDs, 3 optical, floppy, 5 fans) so I opted at around 470W. It may be a bit of overkill (I really only need ~400) but I like the option of upgrades.

 

[LoTeX]

if i recall correctly fans don't eat up much power... (?)

 

[Total Immortal]

I didn't really have a particular system in mind. My parents PII 450 is on it's last leg, and I'm just thinking ahead cause I'm going to just build them their next computer. But I also have plans to build a system for myself (much more trick) so I wanted to see if there was just a guideline I could go with. Basically there's no such thing as too much power? I myself right now have an enermax 550w. I have an AMD XP 2200+, 1 gig ram, 3 HD's, CD,DVD, GeForce4 ti4600, SB Audigy, and I'm probably still over powered.

For the sake of this conversation. Let's say for my I parents I go something like this:

- asus A7V8X-X w/ AMD Athlon XP 2600+
- 512 mg ram
- 40 gig HD
- CD/DVD
- CD/R
- floppy
- ATI radeon 9000 (not the all-in-wonder)
- Soundblaster Live! 5.1

they don't do anything besides surfing the internet, scanning photos, and my step dad makes CD's sometimes. what do you think?

 

[ekÆsine]

an enlight 420watt would do nicely for that purpose. link:

http://www.newegg.com/app/ViewProductDesc.asp?description=17-103-604&depa=0