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Missing PCI-e connectors and 18v Rails with GTX460

Last response: in Components
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September 16, 2010 2:50:46 PM

Hey guys!

I have a 500 W OXZ PSU.

I really want a GTX460, but the PSU doesn't have enough PCI-e connectors:

1 x 20+4-pin ATX (Using)
1 x 4-pin CPU (UNUSED)
1 x 6-pin PCI-E
3 x SATA (Using 2, 1 UNUSED)
4 x Peripheral (ALL UNUSED)
1 x Floppy (UNUSED)

My supply meets the 500 W requirement, but the 12v rail only meets 18 amps, not 36.

+3.3V@30A, +5V@30A, +12V1@18A, +12V2@18A, -12V@0.5A, +5VSB@2.5A


Since I have two rails, but not enough connectors, should I use a molex adapter on two of the peripheral cables?
Or should I look into a new PSU?
a b ) Power supply
September 16, 2010 3:42:43 PM

36 Amps is just what is recommended its minimum power rating is 24 Amps on the 12 volt rail. Your power supply is more then enough for a GTX 460 I went on OCZ website and it even says that prior to 2008 the model you have came with only one PCI-E after 2008 it came with two it also says that it can output a total of 481.5 watts between the two rails so its more then powerful for your needs. Just get an adapter and your good to go.
September 16, 2010 6:12:16 PM

Just make sure that you put the Molex-to-PCIe adapter on the other rail (otherwise you gain nothing). Hopefully it tells you which cables are on which rails.
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September 17, 2010 5:51:22 AM

Okay, cool. I wasn't sure if you could combine amperage effectively.

I already have the OCZ 500W, BTW.

Okay, so I pulled out the plugout chart here.

The only way to get to the 12v1 rail is through the CPU fan, which, thank goodness, I am not using. Can anyone point me towards an adapter for this particular purpose?
September 17, 2010 2:24:14 PM

Uh oh. I looked at your specification chart. You are right, 12V1 ONLY goes to your CPU 12V 4-PIN cable (that's not a fan cable, thats for the CPU). I'm not sure you can tap into that cable, and without that extra 18A, I'm not sure you want to run a GTX460 of a single 18A rail that is shared with the motherboard and all your other peripherals.

Maybe I'm wrong, but I think you need a different power supply.

This is why multiple rails are sometimes bad (not blaming you, blaming the industry). 36A combined sounds good, but not if half of that is reserved for a single component.
September 20, 2010 2:24:12 AM

So there is no adapter readily available for this purpose?

Best solution

a c 144 ) Power supply
September 21, 2010 1:49:58 PM
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Not quite so fast. :) 

Most of the smaller "multi-rail" PSU's really aren't. Get a digital multimeter and measure the resistance from the 12 volt lines (the yellow wires) from each cable to every other cable. If they all measure the same low resistance, you have a single rail PSU. And you will be able to use the adapter safely.
September 21, 2010 7:00:06 PM

jsc said:
Not quite so fast. :) 

Most of the smaller "multi-rail" PSU's really aren't. Get a digital multimeter and measure the resistance from the 12 volt lines (the yellow wires) from each cable to every other cable. If they all measure the same low resistance, you have a single rail PSU. And you will be able to use the adapter safely.


LOL, what? First off, if you do this, make sure to turn-off the PSU. You can't measure resistance on a line with live voltage, it won't work (and you risk shorting something). Second, I don't really know why every piece of documentation (including the wiring spec) would talk about 2 rails when they really use one. Single-rail is a big selling point (especially for OCZ who bought PC Power and Cooling not too long ago).
a b ) Power supply
September 22, 2010 1:59:27 AM

Multi-rail was a big selling point a few years ago too. Times change...
a b ) Power supply
September 24, 2010 1:18:04 AM

ok i think jsc made a good point. most psus only have one real rail. but they market it as two (whos gonna look eh?)
September 24, 2010 4:15:02 AM

Wow guys, thanks!
The other night I opened my box to look at the actual PSU. Turns out that the PDF I posted is far outdated (I really should have noticed the Pentium 4 connector...).
The link that iam2thecrowe posted shows the actual rail designations, that is 12v1 is main mobo + PCI-e and 12v2 is peripherals. I will be good if I need to upgrade my GPU.
September 24, 2010 4:16:20 AM

Best answer selected by zxcvbnm44.
a b ) Power supply
September 24, 2010 5:15:04 AM

This topic has been closed by Mousemonkey
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