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+12V Dual Rail Amperages

Last response: in Systems
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March 24, 2006 1:48:10 AM

Howdy all,

I just got an OCZ600ADJ-SLI with the dual 12V rails.

I am worried though, because the second rail only provides 20A on the molex, sata, and pci connectors. I have a 7200 rpm 120gb WD and a SATA 36gb 10k rpm, two 7900 GT's in SLI, and old 1x DVDRW and CDRW 24x.

According to the eXtreme wattage calculator I'll draw about 18.5A (at max load?) with these devices running on that rail. When I put in 10% values for the capicitor aging and surge compensation It goes up to about 26.41A.

Which figure is more reliable, 18.5A or 26.41A, and if the former, is this too close for comfort?
March 24, 2006 12:08:55 PM

Well on my 7800Gt it has the PCIE connector at the end of the card, which I plugged in to the 2x4-pin HDD molex adaptor so in theory it is drawing power from both rails.

edit: so at max draw, even w/ the 26A it will be split between the both rails so you should be fine - BTW that is a nice PS...
March 24, 2006 6:16:05 PM

I see. Do you have the A8N32-SLI deluxe mobo?

If so did you plug power into the PCI-e on the card and to the EZ-Plug on th mobo?
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March 25, 2006 3:31:08 AM

Nope, I have an eVGA 133-K8-NF41 and an older PCP&C Turbo-Cool 510 ATX that didn't have a pcie connector.

My board also had a 4-pin HDD type molex power connector, that I assume would help out the PCIE slot current, or cpu or both.
March 25, 2006 5:25:29 AM

Right, so did you plug into that molex connector and into the PCI-e auxillary power?
March 25, 2006 6:28:36 AM

Absolutely, since I was a bit paranoid that my power supply didn't have the full 24-pin I plugged in power anywhere I could (the "ez-plug", didn't realize it was called that lol), and the pci-e aux / molex adaptor.
March 25, 2006 6:37:06 AM

it is very important to have ..a pci express connector otherwise your card will draw current from your mobo therefore from your first 12v rail......

so the first rail supplies the cpu (mobo regulators) and the second rail feeds the hdds optical storages...pci express cards...in here the video card consumes a lot comparing to others....

i see you`re worried about the second rail ..... 20 amps for a sli set it quite small indeed ... that will be 240watts cc ... unless you know exactly how much amperage one card needs .. you could only try and see what happens ..... nothing dangerous could happen except same restarts during benchmarks.........
good luck ....
March 25, 2006 9:05:10 AM

Nothing dangerous? Just a bsod and/or reboot?

Yeah 240w aint much even though i know these 7900 gt's apparently use less power than the 7800's did due to 90nm fab.

But doesn't the card draw some of its power from the board (1st rail) and the rest (aux/supplementary) from the 2nd rail?
March 25, 2006 9:09:46 AM

nop..as far as i know all the power is drawn from 2nd rail....
!