Power question.

[Bizkitkid2001]

I have a question about if my power supply is good enough or not. I have the Thermaltake 420watt PSU that I paid $39 for on Newegg about 4 months ago. So far it has been great and I have had no problems, but am still concerned. The list below is what the PSU is powering, so far everything is running and gets power with no shut downs. But I would like to know if I am pushing the PSU to its limit, and if it will hold out much longer.


- 4 IDE Hard Drives
- 1 SATA Hard Drive (Still trying to get this one to work though)
- 2 Burners (CD and DVD)
- Nvidia FX5900NU


I have a secondary PSU powering everything connected to the motherboard and all of my case fans.

So it boils down to, can this PSU handle 5 hard drives, 2 burners, and a power hungy video card? Or am I already testing its limits? I read somewhere that HDs are probably the most power hungy device in the entire system, and thats why I have two PSUs because of the 5 drives.

Thanks,
-Biz

[Martoch]

Great thread about power supplies...it even links to a PSU calculator.

[RamonGTP]

Yes it should be enough. Hard drives don't use THAT much power. I've got a 7200 RPM drive here at its rated at 600mA@5v and 900mA@12 volts. That translates to 3 watts on the 5v rail and 11watts on the 12v rail. So total power usage of 14watts. And the video card, being a NU, really isn't all that power hungry either.

I built a server for a client reciently and I used a 430watt Antec PSU. The server was running 2 7200RPM SATA drives and 3 10,000RPM SCSI drives. Along with a tape backup unit and DVDRW drive. No problems.

[Bizkitkid2001]

on one of the calculators, it says that my 5v needs to be 7.7v. Is that really accurate?

[jokostel]

no.

[JPMiller]

I believe you mean that your specs, according to that calculator, require 7.7 Amps from the +5V rail?
The +5V rail is always WAYYYYY over-powered....
no need to worry about that rail...

You want your main, best PSU to be the one powering the motherboard, drives and Video card, any secondary PSU would best be used on peripherals like fans and lights.

no.

Why do you say that?

[#43 fan]

He meant that your 5V rail shouldn't be 7.7 volts, considering that's way out of spec.

[Bizkitkid2001]

I thought the Calculator said that I would need 7.7volts on my 5v rail to run 5 hard drives, 2 burners, and a 5900. I'll check again.

EDIT: It says AMps, not Volts.

Second time around I selected hard drives closer to mine, and it came out to 8.2amps needed on teh 5v and 7amps on the 12v. 135 watts total.

[RamonGTP]

Another thing to remember is that those calculators overestimate your power needs by A LOT. If you want to know exactly how much power your drives need, just look at them. It will tell you on the label, as mine did. I'm willing to bet your actual power usage with all those drives will be about half what the wattage calculator says you need. Your TT 420 will be more than enough for the entire system.

[JPMiller]

Exactly...
few people need as much power as they think they do...
That TT 420W should be more than enough without the second PSU...

[bombledmonk]

Exactly...
few people need as much power as they think they do...
That TT 420W should be more than enough without the second PSU...

... if you trust thermaltake to put out close to the rated power, some people do some don't.

[JPMiller]

I've been using little else in my builds lately and havent had an issue even in heavily burdened systems...
theyve all been right on spec...
Have you checked your Voltages by using EverestHome?
http://www.techimo.com/photo/showpho...0/ppuser/82591

[RamonGTP]

TT puts out pretty close to its rated output. Either way, the system in question won't draw anywhere near 420watts. My system draws well under 300 watts with the following:

3 Hard drives
1 DVD ROM
1 DVDRW
3x512 PC3200
9800 Pro @ 425/385
Mobile 2600+ @ 2.3GHz
Audigy2 Platinum
PCI NIC (onboard NIC went bad)
Tuner card
Dedicated Video Caputer card
7 case fans
2 cold cathode lights

My PC is hooked up to a power strip that shows power usage, and it shows WELL under 300 watts when the CPU is under load, and that includes the wasted energy as heat by the PSU itself. So the actual system is drawing even less than what the meter shows.