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frozensun

X99 CPU connector,when to plug 4pin,when 8 pin when 4+4 pin possible schematics

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Posted · Original PosterOP

Hi guys,so my problem with issue RGB fans blocking MB for posting was a weird one.

A friend of mine who is into pc repair for 25 years couldn't even understand but he resolve issue after damn 3 hours trying everything.

The other local technician plugged 8pin to the board and my friend who is a PC technician tried all,disconnected all at the end, and after all that he plugged 4+4 on Asus rampage V Extreme instead of 8-pin from PSU to 8-pin on MV like other dude plugged in.

So I'm curious to know,schematics of those connectors on X99,what is the difference between plugging only to 8 pin,plugging only to 4-pin and plugging 4+4 pin (4-pin from PSU to 8 pin on mb plus 4-pin from PSU to 4-pin on mb)?

 

 

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The difference is the amount of current the cable can give to the processor. Powerful processors may demand more current than what a cable with a single 4 pin connector could safely transfer, without overheating or cause significant voltage drop on the cable.

 

EPS 8 pin is the 8 pin connector for the cpu, standard connector. Some power supplies make it possible to split this EPS connector into 2 pieces, each with 4 pin, so that you'd be able to power older motherboards that have or require only a 4 pin connector.

Some motherboards add an extra 4 pin or 8 pin connector besides an existing 8 pin connector - using this one is almost always optional and you really only need to use an extra cable from the power supply if you're into serious overclocking (liquid nitrogen, other such extremes)

 

The 4 pin connector can give 2 pairs x 9A per pair x 12v = ~  216w to the cpu, so for safety reasons and so on, it should be used with processors that consume up to around 175w  ( pretty much quad core cpus)

8 pin connector has 4 pairs and is rated for 4 pairs x 7A x 12v = ~ 336w (you get less current because of the density of wires in connector) so it's enough for any cpu that consumes less than around 300w.

 

 

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Posted · Original PosterOP

So give me an idea why when 8-pin was plugged the RGB leds on fans didn't work?

What that has to do with 8-pin eps on MB?

Besides sata power supply connectors on PSU are on separate lead.

For unknown reason to him and to me,why for my CPU (Xeon 2640 v3) it has to be this way 4+4, not 8pin?

 

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No idea. Maybe the 8 pin cable is faulty and has a short , or maybe you had a brain fart and tried to use a pci-e 8pin connector instead of the EPS connector (you'd have to really force it in to work but I've heard people screwing it up) and these are not compatible, different pinouts.

 

The cpu power connectors are stupid simple ... two horizontal rows of pins, one row has 12v , the other row is ground... so you can picture them as a single wide 12v wire and a single wide ground wire.

On most motherboards those connectors power ONLY the VRM, the dc-dc converter that powers the CPU.

The fan headers are powered from the 12v wires which are in the 24 pin ATX connector.

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Posted · Original PosterOP
33 minutes ago, mariushm said:

No idea. Maybe the 8 pin cable is faulty and has a short , or maybe you had a brain fart and tried to use a pci-e 8pin connector instead of the EPS connector (you'd have to really force it in to work but I've heard people screwing it up) and these are not compatible, different pinouts.

 

The cpu power connectors are stupid simple ... two horizontal rows of pins, one row has 12v , the other row is ground... so you can picture them as a single wide 12v wire and a single wide ground wire.

On most motherboards those connectors power ONLY the VRM, the dc-dc converter that powers the CPU.

The fan headers are powered from the 12v wires which are in the 24 pin ATX connector.

I don't have 8pin,I have 4+4 pin on PSU (and no way that both guys plugged GPU connectors as EPS).

And those 4+4 guy plugged into 8-pin on MB.And the MB didn't even want to POST when RGB controller is plugged in.Which is really really weird.

PSU is GX 650W.

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