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Old 04-11-2018
ryan29 ryan29 is offline
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Default Can someone explain the extra 4 pin connector on a Lenovo S30 motherboard?

Hi,

I recently got my hands on an old Lenovo S30 (0568). The motherboard has a 24 pin ATX connector, an 8 pin CPU connector, plus a 4 pin connector. I've read the 4 pin connector is for 12v to the PCIe ports. Why would they do that? Why can't the 12v come from the ATX connector?

I don't know much about anything power related and I was hoping to move the board into an existing build that has an EVGA SuperNOVA 550 GS power supply. Can I get away with a molex to 4 pin adapter?

I've seen suggestions the 4 pin connector isn't even needed if there isn't much power draw from the PCIe slots. It POSTS without, but I'm reluctant to run it without knowing what the effects could be.

I have 2 (cheap) PCIe SATA cards and can use pretty much anything for a video card.

Any tips?
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Old 04-11-2018
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If it is for the PCIe slots; then yes they can grab power from the ATX 24pin connector but that connector only has 2 wires to supply 12v power to the entire board (except the CPU) so in the case of multiple PCIe devices which use a decent amount of power from the slot (like multiple high end GPUs) it's better to use another connector so you have more wires to supply that 12v power.
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Old 04-11-2018
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Thanks. It works without, but I added an adapter just to be safe. I'm still a bit curious though. How much power could typically be drawn through the 24 pin connector? I've always assumed it would need to power all the PCIe slots to spec, wouldn't it?

Is it possible they added the extra 4 pin connector to split the draw across rails (is it possible to do that?)? The original PSU had 4x 12v rails. I think they were around 16A each (1 for CPU & 4 pin?, 1 for ATX 24 pin?, 2 for 6 pin VGA?).
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If they did the multi-rail intelligently then the layout would be like that with MOLEX and SATA connectors also on the same rail as the 24pin cable.

The thing to keep in mind is that every PCIe slot can supply (according to spec) up to 75w of power.
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Old 07-18-2018
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SATA connectors also on the same rail as the 24pin cable and so every PCEI slot can supply max power of 75w
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Old 07-18-2018
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Quote:
Originally Posted by ryan29 View Post
Hi,

I recently got my hands on an old Lenovo S30 (0568). The motherboard has a 24 pin ATX connector, an 8 pin CPU connector, plus a 4 pin connector. I've read the 4 pin connector is for 12v to the PCIe ports.
You read wrong.

Like most Xeon boards, they provide +12V to the CPU over multiple connectors. In this board's case: an EPS12V and an ATX12V.
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Old 07-18-2018
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Quote:
Originally Posted by jonnyGURU View Post
You read wrong.

Like most Xeon boards, they provide +12V to the CPU over multiple connectors. In this board's case: an EPS12V and an ATX12V.

In a case like this I think using multiple power supplies would be an issue.
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