EPS vs P8 vs P4 for CPU

Question

Can you tell me which of these cables I have to connect to my CPU (i7 8700K) to power it? If it is the p4 or p8 than they are defently to short (if it is the eps I will know more tomorrow) and I have to buy an extension. (Is there anything I need to know/to take care of before choosing one?)

Mother board: ASRock Z370 Extreme 4

Power supply: Dark Power Pro P7

Solution

Can you tell me which of these cables I have to connect to my CPU (i7 8700K) to power it?

P4

P8: The P8 connector is required for multi-processor boards. This provides the processors with extra 12v cable, which is required for stable operation

EPS: The additional 6 pin EPS connector is required for special mainboards in the server and workstation. This plug is available from the 650W model.

As you can see the manual for the PSU indicates the other two connectors are not applicable to your system.

The only connectors you should be using are ATX12V1, ATXPWR1, and CPU_FAN1. Your system will not start unless you have plugged the correct cable into those connectors. It also appears you had your CPU fan plugged into CPU_OPT/W_PUMP which would only be applicable if you had a pump and only after you configured it within UEFI.

ATXPWR1 - This motherboard provides a 24-pin ATX power connector. To use a 20-pin ATX power supply, please plug it along Pin 1 and Pin 13.

ATX12V1 - This motherboard provides an 8-pin ATX 12V power connector. To use a 4-pin ATX power supply, please plug it along Pin 1 and Pin 5.

Manual

PSU - German - Manual

PSU - English - Manual

The manual makes it clear that P8 and EPS is not applicable to your motherboard.

The ATX specification requires the power supply to produce three main outputs, +3.3 V, +5 V and +12 V. Low-power −12 V and +5 VSB (standby) supplies are also required. The −12 V supply was primarily used to provide the negative supply voltage for RS-232 ports and is also used with one pin on conventional PCI slots primarily to provide a reference voltage for some models of sound cards.

Originally, the motherboard was powered by one 24-pin connector. An ATX power supply provides a number of peripheral power connectors and (in modern systems) two connectors for the motherboard: an 8-pin auxiliary connector providing additional power to the CPU and a main 24-pin power supply connector, an extension of the original 20-pin version.

ATX

Be sure P4 is connected to ATX12V1 and the 24-pin is connected to ATXPWR1.

Comments

[baxbear]

Let us continue this discussion in chat.

[Ramhound]

You will want to be sure you plug the 4-pin ATX12V cable into the connector the correct way.

[baxbear]

Just to be sure "Be sure P4 is connected to ATX12V1 and the 24-pin is connected to ATXPWR1." - "and"? Or do I have to decide for one? My P4 cable is too short to connect it, is it possible to use the P8 instead or will it damage the system?

[baxbear]

Just switching the fan from CPU_OPT/W_PUMP to CPU_FAN1 did just change, that the fan now spins permanently but the system still powers down like every 10s and then tries again to start - no monitor output. Also removed everything (HDDs, SSDs, graphic card, sound card...) to prevent different sources of error.

[Ramhound]

I believe my answer is clear. I have answered it based on the documentation that is available to me. I have used my decades worth of knowledge on the subject to formulate this answer. I don't believe I need to clarify anything about the answer. I have used specific words for a reason, I don't feel I should have to explain, that particular sentence. If indicate that P4 should be connected to ATX12V1 and 24-pin ATX cable should be connected to ATXPWR1 I mean exactly that. If I thought P8 should be used instead I would have said something. Contact ASRock technical support for specifics.