PSU. When is enough power enough?

[Fibre Optix]

Okay 2 questions on a PSU.

First I know the PSU power depends on what you have in your rig or what you plan to put in your rig.

So with that said. I want to build a gaming rig. I'm talking about the latest pocessors and vid cards not to mention a few gizmos (Card reader fan control combos, cathodes etc..). I also will want to add another dual chip Video card in the future when the price comes down to double up my video card performance.

1. Should I pick up the biggest PSU I can afford? (which would be an OCZ 700 watt)

2. A guy a Tiger Direct told me that a PSU is not about wattage but the AMps as well. He suggested picking up a 600 - 700 PSU with one that can handle over 30 amps at peak performance. Is that right?

[blue60007]

1) Not necessarily...you won't need a huge power supply if you don't plan on dual cards, where as you'll need a beefier power supply with dual video cards (even then, you probably won't need a kazillion watter.

2) Suprisingly, the guy at TD is partway right (yes, please avoid TD...it's not known for customer service). Yes, it's not all about wattage and you have to look at amperage (on the different rails, 3.3V,5V,12V etc) but you also can't forget the quality of the power supply. But, 30 amps on the 12V rail(s) for a 600-700W PSU is pretty weak. The 700W OCZ I looked at puts out 72 amps on the 12V rails. But, as I said above, you don't necessarily need 700W.

If you are planning on SLI or Crossfire, here's the recommendations (notice the different recommendations for different cards):
http://www.slizone.com/object/slizone2_build.html#certified_powersupplies
http://www.ati.com/technology/crossfire/buildyourown2.html

Some good brands are Antec Truepower-3, FSP, OCZ, PC P&C, Seasonic, Sparkle, Enermax...just to name a few.

[Fibre Optix]

Cool thanks dude.

[Mr.Ferrari]

I also first look at quality then specs.

[David M]

The guy at Tiger Direct was sorta right and sorta wrong. To clarify some terms, power is measured in Watts. Current is not power but the amount of electrons flowing which is measured in Ampres or "Amps". Power in Watts is obtained my multiplying the number of amps times the number of volts.

There are many factors which determine the power and quality of a PSU. You need to look at factors other than claimed power (watts) to sort the good from the bad. Keep in mind that there is nobody keeping PSU manufacturers from stretching the truth or flat out lieing. Although, there are pleanty of PSU manufacturers who are honest and make an excellent high quality product.

Go here if you want to know the excellent manufacturers from the good from the not so good.

http://forum.pcmech.com/showthread.php?t=166869