is 400W/Dual rail at 18A enough for 8800gts?

hey all,

Going to build me a new system as cheap as possible. I want to run a 8800gts 640MB which has this req,
"Minimum 400W or greater system power supply (with 12V current rating of 26A"

I've zeroed in on this Silverstone psu, looks promising at 400W with 18A on +12V1 & +12V.

http://www.silverstonetek.com/products/p_spec.php?pno=st400&area=usa

This is the build:

Duo Core E2180 Dual 2.00 1MB 800 (Going to OC it to 3.6GHz)
Freezer 7 (Socket LGA775)
Asus P5B 965P 16x FSB1333-ATX+GL+S
Corsair PC5400 DDR2 667 1GB (rm90) x2
WD3200KS 320GB SATA 16MB
Winfast PX8800GTS 640 DDR3 320 500 1600
Lite On DVDRW (18X) 18x/8xDL/12xD-Ram (18AP)
Creative Inspire 2400 21W

So, do u all think this is advisable? i still can't figure out the 12V rail thingy.

please enlighten me.
7 answers Last reply
More about 400w dual rail 8800gts
  1. " i still can't figure out the 12V rail thingy "

    It's there in the specs, 29 amps combined, it's enough.
    Read this
    http://www.overclockers.com/articles1452/

    This Corsair for $8 more after rebate , would give you more breathing room with up to 33 amps on the +12v rail.
    http://www.zipzoomfly.com/jsp/ProductDetail.jsp?ProductCode=10006428
  2. The combined 12volt rails on that PSU is good for 29A. It'll work, but you're not leaving much head room.

    You can pull as much as 18 amps from either rail, but not more than 29 amps from both at the same time.

    If it were me, I'd spend a few extra bucks for a 500.
    http://www.newegg.com/Product/Product.aspx?Item=N82E16817256027
  3. As of yesterday, you should only consider the new 8800GT that was just released. It uses less power than the GTS, GTX, and all higher-end ATi cards. It should do alright.
  4. I also think that the 400 w Silverstone PSU is marginal. Specs say that the operating temperature is 0 to 50 deg. C. From the mtbf figures, rated output is at 25 deg. C. (room temperature). Based on data that I have seen from various PSU manufacturers (at least those who do publish data), you need to derate the output by about 1% per deg. C. over the rated operating temperature. That basically means that at 40 deg. C (a more likely operating temp.), your 400 watt PSU turns into a 340 - 350 watt PSU.

    A lot of the "better" PSU's specify full rated output at 50 deg. C.
  5. gwolfman said:
    As of yesterday, you should only consider the new 8800GT that was just released. It uses less power than the GTS, GTX, and all higher-end ATi cards. It should do alright.


    Good point.
  6. Here's your cheapest deal and still get a quality PSU. You can get the 380w version, but is only about $3 cheaper. This one has a little more upgrade path than the 380w EW one, so I'd recommend this one on a tight budget. $60 shipped - $30 MIR = $30!!!
    Antec earthwatts EA430 ATX12V v2.0 430W Power Supply 100 - 240 V UL, CUL, FCC, TUV, CE, CB, C-tick, CCC - Retail
    http://www.newegg.com/Product/Product.aspx?Item=N82E16817371006
  7. Funny, I asked the same question a few days ago, but about a 500W PSU being able to support 2x 8800 640 mb GTS'

    Heres the link to the forum discussion:
    http://www.sharkyforums.com/showthread.php?p=2513366#post2513366

    and heres the link to the PSU wattage calculator I found:
    http://www.extreme.outervision.com/PSUEngine
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