Need Advice of selecting a Power Supply


Mar 19, 2010
Hello Everyone,

I'm going to be building a computer for the first time and I'm not exactly sure how large a power supply I'll need. Any advice on what kind of PSU you'd put in a build like the one below would be greatly appreaciated.

The Build:
Core i7 - 980x
Antec twelve hundred ATX full Tower Case
Hitachi deskstar 1TB 7200 RPM 32 MB Catche
Crucial 64GB SSD
2 x Corsair XMS3 6GB(3x2GB) DDR3 1600Mhz
ASUS Radeon 5970 2GB

I had previously been looking at this power supply:

CORSAIR CMPSU-750TX 750W ATX12V / EPS12V SLI Ready CrossFire Ready 80 PLUS Certified Active PFC Compatible with Core i7 Power Supply

and while I hear corsair is a good brand is there one you would recommend over it? Do you think 750W is enough? too much? too little? Any advice you can give on selecting a PSU would be wonderful. Thanks for taking the time to read this.
The high quality Corsair TX750 is more than sufficient to power your system.

Here are the official power requirements for ATI Radeon™ HD 5970 video card.

ATI Radeon™ HD5970 System Requirements:

PCI Express® based PC is required with one X16 lane graphics slot available on the motherboard

650 Watt or greater power supply with one 75 watt, 6-pin and one 150 watt, 8-pin PCI Express® power connectors

850 Watt or greater power supply with two 75 watt 6-pin, and two 150 watt, 8-pin, PCI Express connectors for ATI CrossFireX™ technology in dual mode

The power supply 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.

I would recommend the new Seasonic X750 Gold certified power supply over the Corsair TX750. It is a newer energy effcieint design that is very quiet. technical reviews were very favorable. I have the X650 Gold model.

With the Antec 1200 case, no other PSU can effectively compete with the CP-850.

It matches other comparable units like the Seasonic X Series, Antec SG Series and Corsair HX series but it handily beats them all in acoustic performance and it's half the price of those units. At $160 for the Antec 1200 already spent, the CP-850 costs you only $84 more.

Compare that with the:

Corsair HX-750 ($140 after $10 MIR)
Corsair HX-850 $190
Seasonic X750 $180
XFX 850W Black Edition ($185)
Antec SG-850 ($204)

The above are all great PSU's but the fact is the CP-850 either matches or exceeds any one of them while being available at only a fraction of their cost.

The CP-850 and SG-850 are the only ones to make the Editor's Choice List here:

The Antec CP-850 is a superlative power supply by almost any standard. Its electrical performance is up at the level of its more expensive brethren, the Signature 650 and 850, and Seasonic's flagship, the M12D-850: Voltage regulation is extremely tight for all the lines at all loads, and the ripple noise is amazingly low.

The noise performance is excellent, with the <400W performance matching or bettering virtually every PSU tested thus far. Above 500W load in our heat box, the noise level goes over 40 dBA@1m, or about the norm for PSUs rated this high. It has the virtue keeping itself extremely cool, however, cooler than any other PSU we've tested at such high loads.

A serious consideration is that in each of the three compatible Antec cases, the CP-850 mounts on the bottom, and the intake for the PSU is quite separate from the rest of the system...... in the model 1200, a direct path can be maintained to the directly opposite, wide-open front vent. This means that our extreme hot box test conditions never apply to the CP-850; in other words, SPCR's test environment is unrealistically hot for the CP-850. Our atypical spot check with a room ambient thermal test showed the CP-850 would reach only 24 dBA@1m at 700W load in a 27°C working environment. This is ridiculously quiet for such high power output.

The above is an obviously unfair advantage for the CP-850... but what of it? Antec has used an integrated systems approach for its CP-850 and its best cases, and if that approach is an advantage over all other case/PSU combinations, then, all the more power to Antec!

For the quiet-seeking computer gaming enthusiast, the CP-850 (along with any of the three compatible cases) is something of a godsend. Fantastically stable power, super low noise at any power load, long expected reliability due to excellent cooling, modular cabling, and all at a price that's no higher than many high end 6~700W models. That you're limited to one of three well-executed high cases from Antec — one mostly for silence (P183), one mostly for gaming (1200) and one that's really an ultimate everyman case (P193) — is not exactly a hardship either.

The CP-850 is non-standard, but compelling, and in its typical application, as powerful and quiet a PSU as anyone will ever need. It could become a game-changing product if compatible cases become more widespread. Should Antec manage to persuade any PSU or case makers to produce CPX-conforming products, it might help breath a new lease on life on the embattled ATX tower case sector. No, ATX is not about to roll over and die any time soon, but it is in a period of decline as smaller, ready-made PCs increasingly dominate along with laptops. Kudo to Antec for taking a chance and creating a unique, compelling product.

And here's some quotes from jonnyguru's site

If the CPX form factor catches on, the CP-850 will be flat out untouchable. It is completely unmatched by any ATX unit on the market I can think of. You'd have to spend twice as much as this thing costs to find the next best thing, performance wise. I'd like to see some better capacitors in there, but you just can't fault the CP-850's performance here.

I don't know how Antec managed something this awesome for such a low price, but they must really want the CPX form factor taking off if this is the performance we're getting.