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Video Card for a Low-power PSU

Last response: in Graphics & Displays
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April 29, 2012 11:39:37 PM

I want to upgrade from a Radeon HD 5450 to something that doesn't force me to play Skyrim at 800x600 just to get a playable framerate. My PSU is marked as 365 watts — not too bad on its own, but the other numbers are the reason I got the 5450 in the first place a few years ago:

+12V: 12A
+5.08V: 19A
+3.33V: 24A
+12Vcpu: 14.5A
+5.08Vaux: 3A
Max combined power of 5.08V & 3.33V is 160W.

Gimme something. Should I risk money on an HD 7750?

(I can't upgrade the PSU because the system is a PoS HP Compaq)
a c 106 U Graphics card
April 29, 2012 11:53:38 PM

you need about 20 amps on the 12+ rail in order to use a 7750
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April 30, 2012 12:03:19 AM

That's what I was afraid of. Is there anything more powerful than the 5450 that can still manage those low requirements?
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a b U Graphics card
April 30, 2012 12:09:30 AM

He has a total of 26.5 amps 12v total. 12 amp availabe on the 12 accesory line and 14.5 amps on the cpu line.
A 7750 system will draw in the neighborhood of 260 watts. He should be fine with it.
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a b U Graphics card
April 30, 2012 12:14:14 AM

You can run a 7750, just don't overclock anything and up the power draw. Ever.
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April 30, 2012 12:19:04 AM

I definitely had no intention of OCing anything, I know well enough that it would be too much. It's good enough that stock for stock, 7750 is an order of magnitude more powerful than the 5450.

I wasn't aware the 12Vcpu counted towards the total. How exactly does it work into the equation? (my best/obvious guess is that it handles the CPU & leaves the other rail with more breathing room)
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a b U Graphics card
April 30, 2012 12:29:57 AM

There is no one answer. It varies from one power supply to the next.
Single rail,Dual rail,multiple rail.
But all have a set limit on the 12v rail(s).
On a single rail it is governed by the wire guage used and over current protction.
On Dual rails it could be 18amp per rail maximum, but a total of 30amp maximum. Meaning if one is pulling 18amp the other can only have 12 amps.
Multiple rails could be one single rail with over current protection on each rail. Or it could be 3 or 4 individual rails.
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April 30, 2012 12:46:07 AM

Best answer selected by Onihikage.
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