Hello all.

Building a new computer, got everything working but the power supply isn't powerful enough and when anything CPU or video intensive runs the computer will shut off. I have a 500W PSU now but I was wondering how much larger to get without frying the system (if that's possible).

Here's what I've got:

ASUS Rampage Formula MOBO
Inter Core 2 Quad Q9550 ~2.8GHz
2 x 2 gig DDR2 (1066 MHz)
NVIDIA GeForce 9600 GT (not SLI but displaying on 2 monitors)
2 HDD (1 sata 1 IDE)
2 DVD R/W (both sata)

Like I said, I've got a 500W PSU now, just looking for how much bigger to get.

Thanks for any and all help!

8 Years
Discussion Span
Last Post by R1pperZ

-Power supply calculator-

This only gives you a minmum wattage requirement, however, the amperage on each of the rails is what's important, and one must keep in mind that for most power supplies, one can't max the current capacity of both the 5v and 12v rails.

Ok now before you go charging off to go get the 500 watt power supply for 12 dollars on ebay there are a couple things to think about. You want to check to make sure that the PSU is made by a well know company (we will get in to that later). The PSU must be AMD, Intel & UL listed. What’s UL? Google it. Last, and very important, the PSU must supply at least 18A on the +12V rail.

I don't want you to be mislead by the calculator I provided above. While it does add up your total power consumption during peak use, it does not help you in picking out the correct power supply. I can not emphasize enough do not base you decision on wattage alone.

That said what else can you do to ensure you will live power trouble free? One of the easiest ways is to stick to the quality brands (which often means more money but less headache). So what are the quality brands? There are quite a few but to name a couple: PC Power and Cooling, Enermax, Sparkle, Antec (TruePower).

A couple of things to distinguish the big boys is temperature and efficiency which kinda go hand in hand. The more efficient it is then the less power it will lose as heat. Also, look for the little extras like adjustable rails, detachable rails, decibel level... etc.

The PSU is easy to skimp on, but if you are a serious overclocker, don't.


I took your advice and tried the PSU calculator and got my results including amps. The calculator told me I would need about 30 amps on the 12V rail. I've been looking at several PSUs and cannot find any that list the amperage on the 12V above 25A.

Now, there are usually 4 12V's listed ( 12V1, 12V2, 12V3, 12V4 ), each at or about 25A, depending on the PSU. Should I add these 4 togeather to obtain the total amperage on the 12V?


Hey redrum, sorry I forgot all about this thread. I have found a couple of PSU's that I think would be good for your system, seeing your components are far from the cheap side I figured you should look to the best to power them to avoid futur issues and leave you room to throw more components in without a worry of power.
Corsair 550W
And if your on a budget I think you'd be straight even with this Corsair 400W.
Hope that helps, i'm no expert but from what I know I think those PSU's would suffice for your system.

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