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How big of a Power Supply do I Need?

by BKennelly / March 10, 2009 3:33 AM PDT

I have been looking at the idea of building a computer when I get enough money and have been compiling a list of parts that I would like in my system and have arrived at the ones below. The only problem is that I haven't been able to figure out, how much power a system like this would need?

Any help or suggestions would be greatly appreciated!

All parts below are from Newegg if you copy the N82E168 number into Newegg you should be able to find more specs on the part if need be

Motherboard: EVGA 132-BL-e758-A1; N82E16813188039
Processor: Intel Core i7 920 2.66GHz; N82E16819115202
Hard Drive: 2 Western Digital 750GB; N82E168221136131
Video Card: 2 EVGA GeForce 9800GT 1GB; N82E16814130440
Memory (RAM): G.SKILL 6GB (3x2GB) DDR3 1333; N8216820231223
with plans to upgrade to 12GB later on
DVD/CD Burner: 2 ASUS DVD/CD Burner w/ Lightscribe; N82E16827135191
Media Card Reader: Super Talent All in 1 Card Reader; N82E16820609145
Case: Cooler Master ATX Mid Tower Black; N82E16811119161
Monitor: Acer 22" LCD Monitor Black; N82E16824009145
Operating System: Windows Vista Home Premium 64bit; N82E16832116488
Keyboard/Mouse: Mircrosoft FA6-00010 Black; N82E16823109161
Speakers: Logitech 2.1 speaker system; N82E16836121014
Pen Tablet: Wacom Bamboo Pen Tablet; N82E16823100045
to come at a later date

Also I have plans to eventually add a internal Bluray burner, and possibly overclock the processor some, Not sure yet.

If you require any more information regarding this feel free to ask.

Once again any help or suggestions would be greatly appreciated.

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The Biggest
by Darton Fury / March 10, 2009 4:20 AM PDT

you can afford.

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700w or better
by ramarc / March 10, 2009 4:56 AM PDT

dual cards call for 600w at a minimum but a quality 750w would be ideal.
corsair 750w:

don't start picking out parts until you're ready to buy. hardware changes quickly and what's a good choice today may be overpriced 6 weeks from now. for example, you've selected video cards that have been superseded. your 9800GT cards are $150 each but the new gts 250 (a rebadged 9800gtx+) is faster and only $129. the extra memory won't overcome the speed difference at 1680x1050. if you must have 1gb cards, that version is $160 each.
gts 250, 512mb:
gts 250, 1gb:

remember that a radeon hd 4850 is faster than a 9800gt and equal to a gts 250. hd 4850x2 1gb are about $260 and 2gb versions are $290.
hd 4870x2, 2gb:

also consider the gigabyte GA-EX58-UD3R mobo. $100 cheaper but practically identical performance and features.

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I'll Consider your suggestions
by BKennelly / March 10, 2009 5:28 AM PDT
In reply to: 700w or better

Thank you very much I will definitely consider your suggestions, just one more question how did you come up with the estimate of watts on the power supply?

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Psu power supply
by phil66 / March 10, 2009 10:57 AM PDT
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PSU Calculator
by BKennelly / March 10, 2009 12:45 PM PDT
In reply to: Psu power supply

Thanks for your help the only problem with the calculator is that it won't do 2 Video cards it only does one so you have to figure out the video card wattage separately and then add it all together.

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nvidia and video card manufacturers give those estimates
by ramarc / March 11, 2009 1:12 AM PDT

evga 9800gtx+ recommendation:
Minimum of a 450 Watt power supply. (Minimum recommended power supply with +12 Volt current rating of 24 Amps.)
Minimum 550 Watt for SLI mode system. (Minimum recommended power supply with +12 Volt current rating of 30 Amps.)
video card manufacturer power requirements are rules of thumb and include the other components in a typical system. that's why the sli recommendation is only 100w more, not doubled.

"system 3" in this article debunking power supply myths is most similar to your system. note that it's peak power consumption is 544W.

lastly, i suggest you skip most power supply "calculators". many are based on reasoning from the 90s (or earlier). today's computers have far different power consumption than a decade ago. now the 12v current is the dominant draw (rather than 5v). and today's hard drives have negligible power drain -- far different than the days when two drives spinning up simultaneously could overtax a 180w power supply.

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Thank you, but
by BKennelly / March 11, 2009 1:36 AM PDT

First off thanks very much for the information.

The only problem with the ( site ) is that it doesn't cover Intel's newer processors such as, the Core i7's, as well as some of the newer graphics card such as, the GeForce 200 series or some of the later GeForce 9 series.

If anyone can come up a website like the one listed above with more recent information covering newer processors and newer graphics cards that would be a great help

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Here's another option (850W) and with the right code it's
by VAPCMD / March 10, 2009 11:40 AM PDT
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Main Power Connector
by BKennelly / March 10, 2009 1:16 PM PDT

On my motherboard it says it needs a 24 pin power connector. Now what exactly does that mean? Does that mean that I can only plug in a 24 pin power connector or could I plug in a 20+4 pin power connector or 20 pin power connector.

Any Help would be greatly appreciated.

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(NT) Yes 24 or 20+4, either works.
by VAPCMD / March 10, 2009 8:34 PM PDT
In reply to: Main Power Connector
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