madass

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May 17, 2009
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This is the system I plan to get-

Phenom II 945/Athlon II 620
ATI 5850
Cheap USD100 Xfire board
One 80GB sata 7200 RPM
4GB DDR3 800
One DVD-RW drive


Can I use a 300 watt supply that I have running around to power the CPU/mobo and get another 200 watter to power the GPU? The 5850's TDP is 151W afaik. But is this possible? I dont want to have to cut down on my CPU/GPU because of PSU constraints, as I am not a frequent upgrader-I upgrade every 4-5 years or so.
 
Solution

Yes, you can.

Should you? No.

1. Haywired lashup to turn on the second PSU.
2. Minor haywired lashup - the small cheap PSU will not come with the power connectors you need, so you will need to use adapters.
3. Physical problem, where are you going to mount the second PSU?
4. Most important - you are going to trust the health and safety of $200 video card to a cheap PSU?

For a few dollars more than a cheap PSU, you can get a good one.

I estimate 12 volt power consumption:
Overclocked quadcore CPU - 10 amps
5850 - 12 amps
2 drives - 3amps max
fans - 1 amp max
for a total of 26 amps.

Corsair 400CX (30 amps on the 12 volt rail, this will work for you):
http://www.newegg.com/Product/Product.aspx?Item=N82E16817139008...

Yes, you can.

Should you? No.

1. Haywired lashup to turn on the second PSU.
2. Minor haywired lashup - the small cheap PSU will not come with the power connectors you need, so you will need to use adapters.
3. Physical problem, where are you going to mount the second PSU?
4. Most important - you are going to trust the health and safety of $200 video card to a cheap PSU?

For a few dollars more than a cheap PSU, you can get a good one.

I estimate 12 volt power consumption:
Overclocked quadcore CPU - 10 amps
5850 - 12 amps
2 drives - 3amps max
fans - 1 amp max
for a total of 26 amps.

Corsair 400CX (30 amps on the 12 volt rail, this will work for you):
http://www.newegg.com/Product/Product.aspx?Item=N82E16817139008

Corsair 450VX (33 amps on the 12 volt rail - I don't think this one is better enough than the 400 to be worth it):
http://www.newegg.com/Product/Product.aspx?Item=N82E16817139003

Corsair 550VX (40 amps on the 12 volt rail - this is what I would get, leaves you a little headroom for expansion):
http://www.newegg.com/Product/Product.aspx?Item=N82E16817139003

Consider the cost of a new PSU as part of the upgrade.
 
Solution

madass

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May 17, 2009
408
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Hmm.....
What if I take a 400CX now, and 2-3 years from now, use a second 400CX to power a 5970 after Xfiring to to the 5850? AFAIK its possible to xfire 5850 with a 5870, and the 5970 is a pair of xfired 5850's right?
I dont care much for wiring lashups. The second PSU will sit on a shelf next to the case. The case is open all the time anyway.