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Single 12 V rail compared to multiple... and more..

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August 27, 2006 2:58:58 AM

So I recently picked up an evga 7600GS agp, put it in my system with a thermaltake TR2, 430, and while the system boots fine.. my monitor will randomly lose power.. so i double checked the the system requirements of the new card and it said 400W psu..so i said ok... but then noticed that it requires a 20A output on the 12 V. and the TR2 is only 18 max. So the search for a new psu begins, my first thought was antec truepower 2.0 550. However looking at that there is only a 19 A output...but on but it has it on two 12V rails. Then i looked and found this, an Ultra V series with 28 amp on one rail. http://www.tigerdirect.ca/applications/SearchTools/item... for almost 50 dollars after rebate.
First off...how would a psu with two 19A 12V rails work compared to one with a single 28A, if it would work at all? Secondly.. i have heard mixed reviews about the quality of ultra psus...so im kind of wondering if i should just keep looking past the good price of it for a better quality, although i cant really spend a lot.
A few other options i found were this mushkin Mushkin HP-550 550W ATX 12V 24PIN SLI Ready ATX Power Supply 120MM Fan, with two 20 A 12 V. anyone know if mushkin makes good psu's? Or i could also go the route of antec smartpower 2.0 as well... or NeoHE which has multiple 17 A....

Any insight would be greatly appreciated... thanks
August 27, 2006 6:19:42 AM

The Ultra you're looking at isn't just an Ultra, it's an Ultra V (for "Value") series. Don't bother looking at it any further.
Dual +12V rails have one dedicated to the CPU, with the other supplying (e.g.) graphics cards. Since the GS is relatively low-power anyway, the +12V requirement it lists is assuming CPU & gfx card will be powered off a single rail. The dual-rail numbers you listed should all be fine. Mushkin is new in PS (top name in RAM, though) and theirs looks fine. Antec's are good. Pick what you like among those.
a b ) Power supply
August 27, 2006 2:50:51 PM

The TR2 you have should power your system just fine. If it's gone bad and you want to replace it for minimum $$$, consider:
FSP AX450-PN 450watt 12v:2x18a PSU 20+4pin $52+8 8/18/06
http://www.newegg.com/Product/Product.asp?Item=N82E16817104954
AFAIK the Mushkin is a good unit. Reviews are good but it's too new for much user feedback. I know the TruePower 550 is good. It also has "fan only" lowered voltage molex fan connectors to slow the fans down and quiet the system. These cost more than you need to spend though.
Are you sure that the 7600GS card is OK? Is its fan spinning?
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August 27, 2006 8:30:15 PM

Well, i assume it is the power supply...and not the card because the power supply really doesnt meet the requirements specified... but maybe it is the card?
When i first boot up my system.. the first screen that usually comes up is the video card (bios?) screen, saying which vid card...and vga bios version etc... that doesnt come up when the 7600 is in... windows loads fine, i can see the desktop.. but any time the computer starts to do work.. like switching tasks or installing drivers, the monitor loses power. (edit: by this i mean the screen goes black, and the LED turns off)

I have a 5700 256 in there right now and it is working fine however...
August 28, 2006 11:56:12 AM

Quote:
Dual +12V rails have one dedicated to the CPU, with the other supplying (e.g.) graphics cards.


Is it then better to buy a PSU with dual 12V rails with 15-20 amps in each than with a single 12V rail that has 20-30 amps for a power-hungry DX10 video card?
August 28, 2006 10:46:47 PM

Probably neither. I would think you'd want to get a dual-rail supply with more than 20A/rail.
a b ) Power supply
August 29, 2006 9:33:22 PM

Actually it makes no difference whether you get one 30 amp rail or two 15 amp rails. It's all DC coming from the same source. Multiple rails allow for smaller feed wires which save $$$ and make routing easier.
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