My PSU only has an 8-pin and a 4-pin (or more like 3 x 4-pin), and the system’s been running fine, but I don’t know what kind of CPU would need two of these. My Epyc 7313p draws ~100-150W of power at any given time. One of these should be plenty.
How to solve getting enough wires?
I bought a 4-pin Molex to 8-pin CPU connector adapter, but I’m wondering if that’s enough. Maybe I should’ve gotten 4-pin Molex to 4-pin CPU? I have two PCIe 6-pin connectors that are also coming completely unused in this server, and there may be some adapter for those to convert to EPS12V.
You’re likely fine if it boots, you can just plug in the 4 pin in the other connector, and the 8 pin in the main connector, it’s probably mostly for higher wattage cpus
The 7313p can be configured to use up to 180w
I thought those were extra pins to power the SOCs on the (consumer) boards. If you are experiencing some instability, you need to plug power in them (if it works without power).
Each 8 pin is rated for 150w. So if you need more than 225W or want more stable power you get 2 8 pins. But generally you can get away with plugging in one.
I would not use a Rolex adapter as the cable is definitely not rated for the current.
I would try to put the 8 pin in the primary port and the 4 pin in the secundary
did you buy a buy a gaming psu to power a server motherboard?.
if so you may want to send it back and get a replacement meant to be used in a rack.
the second 8pin will supply supplementary power to the pci-e slots as well as powering a high wattage cpu.
so unless you have more than half of pci-e populated or are running a 300w+ cpu, you shouldn’t need to plug in the second 8pin.
My total power usage, including 124 SSDs is ~550W during a write operation where every disk and NVMe drive is in use including all 6 SAS controllers except the ConnectX-6 NIC:
I’ve seen it go down to 280W, but I can’t remember if that’s without any SSDs.
I definitely don’t think I’m gonna be hitting 700W anytime soon.
I can confirm that the board runs fine with only one connection using an EPYC 7702p. Ultimately, the power supply that I ended up with had 2x 8-pin connectors, so I have both connected, but I did boot up with one connected with (seemingly) no issues.
From emails with Supermicro:
You only need 1x 8-pin power connector for CPU, either JPWR1 or JPWR2 and 24-pin JPWR3 power connector for the motherboard.
The CPU is only need 1 8-pin power connector. It probably situated on 2 different corners of the motherboard so customer has a choice to plug in whichever suite with the long or short power cable.
Does the 7313p draw similar to the 7702p?
EDIT: Potentially worth noting, although likely negligible: I have SMT disabled, since none of the simulations / software I employ use threading.
I always assumed the extra power is used for the PCIe x16 slots.
This board comes with 5 such slots and with 75W per slot this power has to come from somewhere.
Holy crud; that’s (7702p) a 64-core CPU. Mine’s (7313p) only 16 cores and has a much lower TDP, but also has higher clocks. As far as I understand, this is essentially a server-grade Ryzen 9 5950X.
In response to some other messages:
The reboot issue was either ZFS or TrueNAS, not power-related. More info in that thread.
I’m not sure how much power these LSI controllers use, but only the new 9600 models require separate PCIe power probably because they support up to 6 NVMe drives or 24 x 24Gb SAS. Older models like the 9305 run a lot slower and fit in a lower profile form-factor.
Looks like primary is JPWR1 near the back of the board, has a (very) little label printed on the circuitboard; Near the mounting hole screw.
The other one (by the 24 pin connector) looks like JPWR2 , again appears to be a small label next to it.
You might need a magnifying glass (or take a pic with you cell on max picture quality and blow it up) to read them though.
