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Combine 2 - 12 V rails?

Last response: in Components
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June 1, 2010 3:36:34 AM

I have this silverstone PSU
and I have a 5770 which Toms recommends I use a PSU with at least a 30 A limit.

I was thinking I would combine my two 20A 12V lines into one 12V 40 A line. Has anyone done this? I cant find 6 pin PCIE molex connectors anywhere so i figure ill just have to cut and splice my lines.

Advice? thoughts?

More about : combine rails

a c 139 ) Power supply
June 1, 2010 4:05:38 AM

It's not necessary for you to do anything like that. You're PSU and motherboard are already taking care of that for you.
And you definitely will not cut and splice any lines in your PC.
You'll use a couple 4pin molex connectors to power your 5770.
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a c 139 ) Power supply
June 1, 2010 4:06:12 AM

Your PSU can take 75W from the PCI-e slot. And another 75W from the PCI-e power connector to get all the power it needs.
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a c 139 ) Power supply
June 1, 2010 4:11:47 AM

chico1st said:
I cant find 6 pin PCIE molex connectors anywhere so i figure ill just have to cut and splice my lines.

OK.... just figured out why you can find any 6 pin PCIE molex connectors.
Thats because your SST-ST56F PSU has 2x PCI-e 6pin power leads. You don't need any adapters.


Your PSU connectors.
1 x 24-pin motherboard connector (550mm)
1 x 8-pin EPS12V connector (550mm)
1 x 8-pin EPS12V to 4-pin ATX12V adapter (150mm)
2 x 6-pin PCI-E connector (550mm)
2 x triple SATA connector (500mm +250mm + 250mm)
2 x triple 4-pin IDE & single floppy power connectors
(500mm + 250mm + 150mm + 150mm)
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June 1, 2010 12:31:28 PM

so the fact that toms recommends at least 30 A on the rail and I only have 20 A on it doesnt mean anything?
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a c 139 ) Power supply
June 1, 2010 12:57:59 PM

That 30Amps of +12V is a total amount for the entire PSU . Your combined +12V1 and +12V2 rating is comfortably above that.
While your PSU doesn't quite punch out 40Amps in total it's supposed to be able to provide at least 36Amps +12V.


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June 1, 2010 1:21:00 PM

Best answer selected by chico1st.
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June 1, 2010 1:25:11 PM

the issue im having is that my 5770 crashes unless i downclock it.
downclocking implies less power
there are PSUs with 40 A on the 12 V rail
mine doesnt have that, you think that the PSU can push enough current through the PCIE slot to suffice?
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a c 139 ) Power supply
June 1, 2010 1:36:19 PM

Have you plugged in the 6pin PCI-e power connector from the PSU to the video card?
Your card is getting 75w (6.5A) from the PCI-e slot and 75w from the PCI-e adapter from the PSU.
And you've read the full load requirement is around ~108watts.

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