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PSU - connectors for 2 graphics cards

Last response: in Components
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November 29, 2011 2:09:17 AM

I've got 2 graphics cards, a 4890 and 570, and an Antec EA650w. Im wondering on what connectors to attach to them.

The psu has 2-6 pin pcies and an 8 pin, both cards need 2 - 6 pins. Im not worried about how much power is used vs what the psu can do, im worried about which plugs to do it right.

Will 1 - 6 pin and 1 molex-6 pin in each work, or do I need an 8 pin splitter to 6 pins?
a c 1167 ) Power supply
a c 540 U Graphics card
November 29, 2011 4:56:51 AM

The only PCI-E connectors on the Antec EarthWatts 650 (EA 650 - EC) are one 6+2 Pin PCI-E connector and one 6 Pin PCI-E connector.

The 8 pin connector you must be referring to is the 8 Pin EPS 12V connector. This is used to power the CPU on most current motherboards.

You'll need to use at least two dual 4-pin Molex to 6-pin PCI-E power dongles that are usually included with the graphics card if its a reputable brand.
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November 29, 2011 4:10:42 PM

Well the computer turns on fine, and I have faith that's the second card has enough power, however the first card, a gtx 570, I'm a little bit more weary of putting it under load.

My understanding of the rails stated that both pci connectors share a 22 amp rail. Being 12 volts, I'm thinking that it will be able to handle about 264 watts. In addition the pcie slots in the motherboard bring out 75 watt each.

If it evenly splits, im worried, if it intelligently splits I'm golden.

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a c 1167 ) Power supply
a c 540 U Graphics card
November 29, 2011 5:19:34 PM

Antec EarthWatts EA-650 +12V rail load distribution:

+12V1 limited to 22 Amps max.: CPU (i.e. 8-pin EPS and 4-pin ATX12V connectors)

+12V2 limited to 22 Amps max.: motherboard and peripherals (i.e. 20+4 pin ATX, 4-pin Molex, 4-pin FDD, SATA power connectors)

+12V3 limited to 25 Amps max.: 6-pin and 6+2 pin PCI-E connectors

Antec EarthWatts EA-650 has a maximum combined +12V1, +12V2 and +12V3 continuous current rating of 45 Amps.

The Radeon HD 4890 will have a realistic current draw of 12.5 Amps from the +12V rail under full GPU load.

The GeForce GTX 570 will have a realistic current draw of 18 Amps from the +12V rail under full GPU load.

I would hook up the 6+2-pin PCI-E connector to the GeForce GTX 570 and the 6-pin PCI-E connector to the Radeon HD 4890.

Hook up one dual 4-pin Molex to 6-pin PCI-E power dongles to the GeForce GTX 570 and another one to the Radeon HD 4890.

This should result in better load distribution.

I don't think either of these graphics cards will draw much power through the PCI-Express slots if they've been designed properly.
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November 30, 2011 12:04:54 AM

Best answer selected by MasterMace.
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November 30, 2011 12:06:29 AM

Thank you much. So to understand, the 8pin EPS and 4pin ATX both run off the same rail? Interesting...
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a c 1167 ) Power supply
a c 540 U Graphics card
November 30, 2011 12:33:32 AM

MasterMace said:
Thank you much. So to understand, the 8pin EPS and 4pin ATX both run off the same rail? Interesting...

When jonnyGURU.com did their review on the Antec EarthWatts EA-650 that is the exact rail distribution they found when they did the tear down of the PSU.
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