Question Could dual Xeon run each on 4pin EPS Cable?

[ketrab]

PSU came with single 8pin(2x4 split) EPS cable.

Motherboard comes with 2x8pin connectors.

Do you guys see a problem if I split the 1x8pin into 2x4pin from the PSU and power each CPU with only 4pin.

I believe the max 4pin draw was around 190watts vs e2697v3 shows max TDP of 145W so theoreticaly should be fine but I have never worked with xeon before and just thought of any caveats or potential damage?! No OC in mind obviously.

So I was thinking of grabbing 4pin CPU extensions cables to split i.e like this:

Amazon.com

Thank you in advance!

 

[kanewolf]

PSU came with single 8pin(2x4 split) EPS cable.

Motherboard comes with 2x8pin connectors.

Do you guys see a problem if I split the 1x8pin into 2x4pin from the PSU and power each CPU with only 4pin.

I believe the max 4pin draw was around 190watts vs e2697v3 shows max TDP of 145W so theoreticaly should be fine but I have never worked with xeon before and just thought of any caveats or potential damage?! No OC in mind obviously.

So I was thinking of grabbing 4pin CPU extensions cables to split i.e like this:

Amazon.com

Thank you in advance!

IMO, no you won't be "OK". You need a new power supply that supports the motherboard you intend to use.

 

[ketrab]

IMO, no you won't be "OK". You need a new power supply that supports the motherboard you intend to use.

I thought that 8pin is just supplemental, CPU TDP will never reach 4pin power.

 

[kanewolf]

I thought that 8pin is just supplemental, CPU TDP will never reach 4pin power.

Average power and instantaneous power are usually very different. TDP is average, but what type spikes are required is what needs to be supported. Those plugs may also support the RAM power or other things.

 

[bill001g]

You are going to have to find some site that actually documents the what the maximum watts the 8 pin connector can deliver.
Lets say the motherboard splits the power itself. You would still be drawing almost 300 watts total. I think that is above the amount of power a single 8 pin connector is allowed to deliver. It is mostly about the size of the wires. Worst case they melt but the other issue is you will get lower voltages when you try to draw too many amps through a wire.

If I remember correctly the 8 pin was something like 250 watts but I don't know why I think that.

 

[Misgar]

I found this technical guide and I'm trying to interpret the EPS12V section on page 16.
https://www.techpowerup.com/articles/160/images/EPS12V_Spec2_92.pdf

Systems that require more then [sic] 16A of +12V current to the baseboard will require this additional 2x2 power connector. This is due to the limited +12V capability of the 2x12 baseboard power connector. +12V4 will power the 2x2 connector.

If I understand this correctly, a 2x2 connector (half of a "standard" EPS12V 8-pin connector) is capable of supplying 12V at 16A, i.e. 8A for each yellow/black pair of wires.

N.B. I'm assuming here we've got an old style ATX power supply with coloured wires instead of all black wires, as seems more popular in Corsair PSUs.

The document continues with:-

Systems with 16xDIMMs and/or dual graphic cards will require the +12V5 output and added +12V5 2x2 connector.

I take this to mean the optional +12V5 rail provides an additional 4-way (or 8-way) supply to motherboards with more than one 8-pin EPS12V connector.

Since there are four pairs of yellow/black wires in an EPS12V 8-pin connector, the total current will be 32A, so 12V x 32A = 384W, unless I'm mistaken.

My conclusion is each 4-pin connector is rated at 12V/16A, i.e. 192W.

If you connect your two 4-pin connectors to the motherboard in any fashion, it can draw up to 384W safely.

Whether or not the BIOS objects to having only two pairs of 4 wires connected to the two 8-way EPS12V connectors is a different matter.

Using only two 4-pin connectors will result in double the "volt drop" down the wires, and greater ripple voltage during short duration, high current transients.

The benefit of powering all 8-pins in each connector is you end up with only half the ripple voltage (which is better).

I agree the ideal situation would be to fully populate all sections of the EPS12V connectors on your motherboard, but I've "got away" with fitting a 4-way cable into an 8-way motherboard, as per the old computer I'm using at the moment.

 

[thestryker]

Check what your motherboard says as to whether or not you can get away with it. Many systems worked fine with 4 pin instead of 8 pin you just have to make sure whether or not you have one of them. If it doesn't specify then I'd suggest against doing so.

 

[kanewolf]

Check what your motherboard says as to whether or not you can get away with it. Many systems worked fine with 4 pin instead of 8 pin you just have to make sure whether or not you have one of them. If it doesn't specify then I'd suggest against doing so.

Server motherboards are less forgiving than desktop boards.

 

[ketrab]

Check what your motherboard says as to whether or not you can get away with it. Many systems worked fine with 4 pin instead of 8 pin you just have to make sure whether or not you have one of them. If it doesn't specify then I'd suggest against doing so.

Its a custom oem motherboard that works without 8pins CPU since it also has 6 pins on the sides that supplement both pcie lanes + cpu but has an option of 2x8pin

 

[ketrab]

You need to read these threads a bit better. You only have a single 13600k he is talking about running 2 xeon cpu chips. These older server cpu took a lot of power.

yes 2xe2697v3

 

[PhysX_HW]

PSU came with single 8pin(2x4 split) EPS cable.

Motherboard comes with 2x8pin connectors.

Do you guys see a problem if I split the 1x8pin into 2x4pin from the PSU and power each CPU with only 4pin.

I believe the max 4pin draw was around 190watts vs e2697v3 shows max TDP of 145W so theoreticaly should be fine but I have never worked with xeon before and just thought of any caveats or potential damage?! No OC in mind obviously.

So I was thinking of grabbing 4pin CPU extensions cables to split i.e like this:

Amazon.com

Thank you in advance!

It may turn on, but some boards check the presence of an 8-pin power connector and won't even turn on if only 4-pin cables are used. You may be able to get an adapter that converts two 6-pin PCIe cables to one 8=pin CPU power connector. But you should only do that if the PSU has enough power, meaning at least 500W, plus however much your GPU needs.