Which Power Supply to get!


Apr 17, 2010
Hi guys, was wondering if anyone could help me decide on a good power supply? and perhaps calculate exactly how many watts my computer system will require?

Here is a list of the components from my new build:

Cooler Master HAF932 High Air Flow Full Tower

GIGABYTE GA-X58A-UD3R LGA 1366 Intel X58 SATA 6Gb/s USB 3.0 ATX Intel Motherboard

MSI R5770 Hawk Radeon HD 5770 1GB 128-bit GDDR5 PCI Express 2.1 x16 HDCP Ready CrossFireX Support Video Card


OCZ Gold 6GB (3 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Low Voltage Desktop Memory Model OCZ3G1600LV6GK

Western digital caviar black 7200 rpm 1tb internal hd
but i also have 2 external hard drive i will be connecting to the system, as well as an old 80gig, and an old 150 gig internal hdd. with future plans of more western digital caviar black 7200 rpm 1tb internal hdd to purchase as well.

can someone help me calculate the watts required for this system?

originally i had this psu selected for purchase:
CORSAIR CMPSU-750TX 750W ATX12V / EPS12V SLI Ready CrossFire Ready 80 PLUS Certified Active PFC Compatible with Core i7 Power Supply

however, now i found a few 1000watts psu that are both 80plus and continuous:

Rosewill BRONZE series RBR1000-M 1000W Continuous@40°C, 80Plus Bronze Certified,Modular Cable Design,ATX12V v2.3/ EPS12V,SLI Ready,CrossFire Ready,Active PFC"Compatible with Core i7, i5" Power Supply


Antec TruePower Quattro TPQ-1000 1000W Continuous Power ATX12V / EPS12V SLI Certified CrossFire Ready 80 PLUS BRONZE Certified Modular Active PFC "compatible with Core i7/Core i5" Power Supply


80 plus and continuous are two important things to look for when buying a psu right? the original 750w did have 80plus, but not continuous.

if anyone can help me calculate the power needed for running my system, and recommend a good psu, i would really appreciate it.

how are these 1000w psu? they are only 30-40 bucks more than that 750w without continous.

and is it better to have a powersupply that runs on 1 rail, or 4 rails?

oh and should i buy a cpu cooler with such a system i am building? instead of using the stock cpu cooler? i will not be overclocking the CPU.


Apr 17, 2010
isn't it better to get one that's 80plus and continuous?

is 650 really enough? i'll be running a lot of hdd
i did a rough check on newegg's calculator. it says i need about 700w or so... but if i want to put more hdd in the future. wouldn't 1000w be better?
You don't need anywhere near 1000W for that system. You didn't answer SAAIELLO's question about crossfire. Hard drives hardly use any power. I'm currently running five hard drives in a highly overclocked system on a Corsair 520W PSU. I agree that a quality 500W PSU would be plenty for that system and a quality 650W would allow for any future upgrades you could ever want.
Here are the official ATI power supply requirements for the ATI Radeon HD 5770 and 5750 video cards:

450 Watt or greater power supply with one 75 watt, 6-pin PCI Express® power connector recommended

600 Watt or greater power supply with two 75 watt, 6-pin PCI Express® power connectors for ATI CrossFireX™ technology in dual mode

The recommendations are for an entire pc system.

Corsair and Seasonic are two brands that have a reputation for high quality power supplies that consistently earn high marks in technical reviews. They are reliable, stable, and come with a 5 year warranty. Some of the newer models come with a 7 year warranty.

If you plan on installing a second ATI Radeon HD 5770 video card, then I recommend the Seasonic X-650 Gold Certified psu:


Here are links to competent technical reviews:




I have the Seasonic X-650 Gold in my new personal pc. I can confirm it is a quiet power supply and that voltages are rock steady during torture tests.


Apr 17, 2010
but that's only the watts required for the gpu though.

there's also the motherboard, 6gigs of ram, and many hdd that are connected to that system though.

what will be the power requirement for those combined?

and what's a continuous psu? or 80plus?
Like JohnnyLucky said, those requirements are for the entire system.

There's no such thing as a "continuous psu". What that means is that the PSU can run continuously at its rated wattage level while cheap PSU's can only do it for a very short time before blowing up.

80 Plus refers to the efficiency of the PSU. An 80 Plus certified PSU runs at at least 80% efficiency. 80 Plus Bronze, Silver, and Gold PSU's are even more efficient. A more efficient PSU means the PSU will draw less power from the wall and will run cooler because it isn't wasting as much power as heat.
syrianrue - The requirements I posted are for an entire pc system. That includes all components like the motherboard, memory, drives, fans, and any other components you may have. The ATI Radeon HD 5770 is an energy efficient video card that does not require very much power. :D

I recommended the Seasonic X-650 which is an 80+ Gold Certified psu. In terms of energy efficiency the 80+ Gold Certified psu's are the best you can get. :D

shortstuff is correct about a high quality power supply being able to run continously at it's rated wattage level for long periods of time. Low quality power supplies typically cannot do that.

Henry Chinaski

Mar 16, 2010
The Seasonic x-650 is an excellent choice for you. Don't worry about the power consuption. You will have more than enough.
Anyway, the Corsair HX750 is a great choice too, but you don't need so many watts and the X-650 is better.