New to Building PCs, how much power will I need?

[veok]

New to Building PCs, 750 watts enough?

Hello!

I'm trying to build a PC for the first time, and I'm finding it a little confusing to determine if the PSU I've selected is beefy enough to serve my needs.

Case:
Antec 902 (It's got some built-in fans that need power, I believe)

CPU:
Intel Core i7-930 Bloomfield 2.8GHz LGA 1366 130W Quad-Core Desktop Processor BX80601930

Video Card:
TWO EVGA 01G-P3-1465-AR GeForce GTX 465 (Fermi) 1GB 256-bit GDDR5 PCI Express 2.0 x16 HDCP Ready SLI Support Video Card to be hooked up in SLI.

DVD Drive:
SAMSUNG 24x DVD Burner - Bulk SATA Model SH-S243N/BEBS LightScribe Support - OEM

Aftermarket Cooling:
COOLER MASTER Intel Core i7 compatible V8 RR-UV8-XBU1-GP 120mm Rifle CPU Cooler

Motherboard:
ASUS P6X58D-E LGA 1366 Intel X58 SATA 6Gb/s USB 3.0 ATX Intel Motherboard

RAM:
CORSAIR DOMINATOR 6GB (3 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Triple Channel Kit Desktop Memory Model TR3X6G1600C8D

Hard Drive:
HITACHI Deskstar HD31000 IDK/7K (0S00163) 1TB 7200 RPM SATA 3.0Gb/s 3.5" Internal Hard Drive


And finally, the PSU:
Antec EarthWatts EA750 750W Continuous Power ATX12V version 2.3 SLI Certified CrossFire Ready 80 PLUS Certified Active PFC ...


Again, no experience at all calculating power requirements.

I found nVidia's SLI site, and it suggested a 750W for two gtx470 cards, which is why I wound up going with a 750W model. But now I'm feeling paranoid, worried that it won't be enough.

Any technauts want to weigh in on this?

 

[EarthDog]

Well, I would actually get a single GTX480 and skip the SLI personally...(doesnt it cost the same anyway but with less hassle and power consumption?)

Anyway, Im sure that PSU will be fine, but there are better out there.

Corsair 750TX/HX
Seasonic AX750

I would go with those over that Antec Earthwatts.

EDIT: I checked on newegg and one 480 is cheaper than 1 465....

 

[nightelph]

Edit: Earthdog beat me to it.

eVGA's site recommends a PSU with 38amps on the 12V rail for a GTX465. Since you want two cards I'm guessing you'll need to clear 76 amps on the 12V rail. Someone correct me if I'm wrong please, this isn't my strongest area.

 

[decoste007xt]

Well, I would actually get a single GTX480 and skip the SLI personally...(doesnt it cost the same anyway but with less hassle and power consumption?)

agreed!

 

[EarthDog]

38A would be for the ENTIRE system, and since you are not putting in two entire systems, that 76A requirement is awfully high...(912W!!!)

I would add the TDP wattage (then convert to amps) to that 38A number. TDP on that card is around 185W (185/12=15.4A) so around 53A would be sufficient which both those PSU's listed have covered easily.

 

[veok]

Well, I would actually get a single GTX480 and skip the SLI personally...(doesnt it cost the same anyway but with less hassle and power consumption?)

EDIT: I checked on newegg and one 480 is cheaper than 1 465....

I got the two 465s when they were on sale, so it was slightly cheaper. I looked around at comparative reviews, too. Couple reviews have 465 SLI > a 480. Like so: http://guru3d.com/article/geforce-gtx-465-sli-review/1

 

[EarthDog]

Sure it beats it but.....meh, SLI/Crossfire FTL (too much power use, never 2x return on 2x price). I assume you are rocking a nice 24" 1920x1080/1200 monitor?

 

[veok]

Almost. It's a 23' 1920x1080 / 20,000 (Dynamic).

I was a little confused by your use of "both" in your previous post, EarthDog. Did you mean "any"? I'm not dead-set on the Earthwatts, and, indeed, had a Corsair 750x picked out, but wound up going with the Earthwatts because it was slightly cheaper. I think I'd only return it if it couldn't provide enough power.

Follow up question: If I was trying to overclock the 930 up to 4.0 ghz, would that necessitate a large increase in power as well?

 

[EarthDog]

Both as in either or would be fine.

I wouldnt return it, it will be just fine. Large increase, not really, but an increase none the less. Either PSU listed would still be fine with an overclock on the CPU.

Im just not a huge fan of SLI and Crossfire and an even bigger 'hater' of midgrade GPU's SLI'd/Crossfired when one can do the job VERY easily at your resolution with less power use, noise, and always getting 100% return on your investment.