sapphire hd 7790 dualx oc on 450w psu double rail 12v 15a???

Tamoho Yamaki

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Thanks for reading and pls answer
my spec:
i3-550 3.2
4Gb 1333 ram
sapphire hd 7790 dualx oc
1 HDD 750gb nothing more
PSU powerman 450w with double rail 12v 15a in total 12v rail supply 320w
My question is: Is that enough power and safe for my pc when full load?? because i know multi rail PSU dont share their Wattage to each other. May be 12v1 is exhausted while 12v2 is still under 50% or less loading.
 
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That PSU is one I have never heard of. But those specs (+12v @ 30A/320W) would seem to indicate it will handle that 85W card plus the rest of the system. Does the PSU have a 6 pin cable?
Btw, how do you know the 12v1 rail is fully loaded and the 12v2 rail is not? Multi channel +12v rails are not always on their own circuit, they are just different taps off the same transformer. http://www.jonnyguru.com/forums/showthread.php?t=3990

clutchc

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That PSU is one I have never heard of. But those specs (+12v @ 30A/320W) would seem to indicate it will handle that 85W card plus the rest of the system. Does the PSU have a 6 pin cable?
Btw, how do you know the 12v1 rail is fully loaded and the 12v2 rail is not? Multi channel +12v rails are not always on their own circuit, they are just different taps off the same transformer. http://www.jonnyguru.com/forums/showthread.php?t=3990
 
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holyprof

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That power supply must be one of those cheap white-box brands. Still, if it delivers the specifid current, it will be enough to power your system. Just dont try to overclock anything.

According to Intel specs, the CPU has a 73W TDP http://ark.intel.com/products/48505/Intel-Core-i3-550-Processor-4M-Cache-3_20-GHz

The 7790 draws 100W at synthetic load and aroound 70W during intensive 3D load.
http://www.techpowerup.com/reviews/Sapphire/HD_7790_Dual-X/24.html

presuming that CPU is on rail 1 and GPU on rail 2 that would give:

Rail 1 : 73W / 12V = 6A
Rail 2: 100W / 12V = 8A

Even if the rest of the system pulls 50W (highly unlikely) you are covered.

Consider getting a good 420 or 500W PSU from a reputable brand. Cheap PSUs tend to degrade fast and can lead to instability and even damage your PC.
 

Tamoho Yamaki

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May 31, 2015
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Tamoho Yamaki

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May 31, 2015
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In here http://www.playtool.com/pages/psumultirail/multirails.html they said the 12v2 rail power cpu and 12v1 rail power everthing but the cpu. So my i3-550 use only 73 W on 12v2 15a which can supply less than 180W so does that mean 107W left on the 12v2 cant be used?
 

holyprof

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Most PSUs have both rails usually hooked on the same converter, they just separate into 2 rails for overcurrent and short circuit protection. You can't exceed the 15A per rail though.

Just to sum it up:
Rail 1 12V, 15A = 180W max
Rail 2 12V, 15A = 180W max

Rail 1 + Rail 2 = 320 W max

So the answer is yes, with CPU pulling 73W max, the other rail can supply the full rated 15A load.