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i have 2 ,12 volt rails do the amps combine or can i combine them?

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June 30, 2008 6:46:28 PM

i have 2 ,12 volt rails do the amps combine or can i combine them? Well i dont have it yet, its on its way from newegg.

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

that is what i just bought, i need 27 amps for my Geforce 7950 GX2 and ive only been giving it 18 amps, which actually is doing ok for it. last PSU was 380 watts and something i just thought about was, does overclocking a cpu and gpu take alot more power? like 100's of watts of power?

Any way does the amps combine or can i make it combine somehow? And how do i tell which molex connector has what amps on it?
June 30, 2008 7:00:30 PM

Your total amps is the two rails added togather. A graphics card will be on one rail and can not pull more amps then that rail will deliver. Their is no way to combine the amps from multiple rails to feed to one card. If your video card takes mutiple power inputs you could use one from each rail which would spread the load out.
June 30, 2008 7:18:17 PM

1833924,2,90365 said:
Your total amps is the two rails added togather[.quotemsg]


No this is incorrect, it is the total wattage provided to the rails divided by the voltage.

Eg: A 500w PSU provides 400w to 2 18amp v12 rails, so its

power = voltage x current

current = power / voltage

400w/12v=33A

So it is not the same as just adding the rails amperage rating together.
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June 30, 2008 7:42:07 PM

djcoolmsterx is correct.

Also, it depends if the psu maker included current limiters on each 12v rail. If limiters are on each rail then each rail can only supply the amount of amps as rated by the psu maker as noted on the psu label. If the psu does not have current limiters then you can calculate the total amps for the 12v rail as djcoolmasterx mentioned.
June 30, 2008 7:46:12 PM

Um, that COOLMAX is weaksauce. It doesn't even have any PEG connectors, but you seem to be aware of this fact...

And yes, overclocking can really ramp up your power consumption. No offense but you have made a very poor choice.

On the plus side if you're an American the 4th is coming up. Hook that sucker up and overclock it like there's no tomorrow. You'll save money on fireworks :) 
a c 139 ) Power supply
June 30, 2008 8:38:43 PM

chaosgs said:
does overclocking a cpu and gpu take alot more power? like 100's of watts of power?

Yes it can if you're going for top overclocks with fairly power hungry CPU and GPU. In this chart the Q6600's power requirements at 3.6 OC had the system requiring 140watts extra just for the CPU overclock alone.

a c 121 ) Power supply
June 30, 2008 9:03:18 PM

Hmmm, Coolmax...tier-5, "Do not buy." According to the label, the combined wattage on the two rails should not exceed 380W; a little less than 32A. Since it is tier-5, take 60% of that; back down to ~19A. Load it any higher, and homerdog's observation about money saved on fireworks applies, but then you'll need to spend more on the parts the PSU takes with it.
June 30, 2008 9:04:27 PM

And Careful how the PSU is rated.

Some of the reviews indicate that it's not a "Real" 500w PSU.

Most "Good" manufacturers list the Wattage as the maximum sustained power the PSU can reliably supply. However, it's possible to safely exceed that value up to another value for brief periods of time. They will list a second "Max" value in the detailed specs someplace.

New Egg tends to not make the distinction. Even though Corsair, PCP&C, and Seanic all support higher "Max Values" beyond their "Rated" wattage they only list the Rated under "Maximum".

Other who supply lower quality will try and fool you by not listing the max sustained wattage.

I would get a new PSU.
a c 137 ) Power supply
June 30, 2008 9:28:17 PM

On the spec sticker in the newegg photos,, your unit shows a max of 380w to the 12v rails. That is 380/12 = 31.6 amps, not exactly additive.
In addition, low quality psu's will only deliver their maximum wattage at room temperature, about 25c. In the case, that is not realistic when installed in a case. Return it if you can for a better unit. A cheap psu is not the place to save money. Most multirail psu's are really only one rail, just limited to how much current can be delivered to the rail divisions.
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