I have a NORCO RPC-4224 with a "01 SAS 12Gb v1.3" backplane and a 1000w seasonic power supply but only has 3 peripheral sata/molex connectors on the back that according to seagate only can handle 5 amps each and 15 amps in total. If I want to fill this case with 24 drives that will not be enough. I know that on my 45drives av15 backplane only has 12v supplied to it. Does the NORCO RPC-4224 require the 5V pin on the molex connector? I was thinking if the backplanes do not require 5 volts and only need 12 volts I could make custom cables using the PCIe/CPU connectors.

the drives require 5V, backplanes that don't require 5V are converting 12V to 5V on the board.
Looking at a few images online for this board, it doesn't look like it is doing this conversion.

You should be able to spread the load across multiple peripheral cables, I've never seen a 1000W PSU with less than 20A on the 5V rail.... some even go up to 25A

Its not the 5V I'm worried about. According to Seasonic the peripherals are only good for 5 amps for the 12v pin each. That's not enough when each drive is >1 amp at 12v. It looks Like I'm going to have to make a custom cable using the 12v from the PCIe cables and 5v from the molex. Seasonic told me that each pin on the PCIe connector is good for 8 amps and on my PS there are 3 unused CPU/PCIe connectors with 4 12v pins each. That makes 96 amps at 12v. Since I am not going to have a GPU that requires power I can use those connectors.

That's good you have insight to connect more connecter pin for power draw.

Edited November 6, 2025Nov 6 by Vr2Io

I'm assuming you have spare sata cables on your PSU, in which case it would be easier to modify your sata perif cables to use molex 4pin... or get additional molex cables from Seasonic supplier (same psu side pinout as sata typically).

Or you can buy push on connectors, and modify what you have.

On 11/5/2025 at 7:54 PM, tjb_altf4 said:

I'm assuming you have spare sata cables on your PSU, in which case it would be easier to modify your sata perif cables to use molex 4pin... or get additional molex cables from Seasonic supplier (same psu side pinout as sata typically).

Or you can buy push on connectors, and modify what you have.

It isn't a matter of how many molex/sata cables I have, it's a matter of how many 12v amps on that the peripheral ports on the PSU can handle. It seems that the peripheral PSU ports can't hand the 12v amps but the GPU/pcie ports can but don't supply 5v. So I would have to make a custom cable that takes the 12v rail from the pcie port and the 5v from the peripheral port. I have not done that yet but will when I expand my array.

1 hour ago, sgibbers17 said:

It isn't a matter of how many molex/sata cables I have, it's a matter of how many 12v amps on that the peripheral ports on the PSU can handle. It seems that the peripheral PSU ports can't hand the 12v amps but the GPU/pcie ports can but don't supply 5v. So I would have to make a custom cable that takes the 12v rail from the pcie port and the 5v from the peripheral port. I have not done that yet but will when I expand my array.

The psu will have a common 12V rail design, the backplane you are hooking it up to will (likely) also have a common 12V rail... you're overthinking it.

I'm not sure what evidence your statement "It seems that the peripheral PSU ports can't hand the 12v amps" is based on.

IMHO your considerations should be:

• will the PSU handle the overall 12V and 5V load (and 12V surge peak at start-up for HDD motors)?

• will the cables from PSU to backplane have sufficient headroom for continuous use and any transient usage peaks.

Edited January 13Jan 13 by tjb_altf4

1 hour ago, tjb_altf4 said:

I'm not sure what evidence your statement "It seems that the peripheral PSU ports can't hand the 12v amps" is based on.

IMHO your considerations should be:

A Seasonic engineer told me via email that the peripheral ports can't handle that amperage but the pcie port can for my specific PSU. They gave me a amperage per pin on each of the different ports. This was mentioned in a previous post.

19 hours ago, sgibbers17 said:

So I would have to make a custom cable that takes the 12v rail from the pcie port and the 5v from the peripheral port. I have not done that yet but will when I expand my array.

That's fine, you could do it later. I agree if only three 12v wire for 24 disk doesn't enough ( in fact 5v also not enough ), module cable even make it worst.

I use non-modual PSU and it have enough cable to connect backplane ( 4 independent molex for 16 disks )

If need I will modify i.e. soldering wire in PSU module backplane to fullfill my requirement. I always modify electric appliances.

For your original question, NOROCO backplane need 5v provide, I don't found they have extra DC to DC converter on PCB.

Edited January 14Jan 14 by Vr2Io

Thanks, I think there is a trend to have more pcie and the new 12v GPU connectors on PSUs, the old seasonic power supplys 520w/750w had 4/5 sata/molex ports and 4/6 pcie/CPU ports.

As for the 5v header not being enough according to the data sheets that I found for my HDD and the seasonic email there is enough head room for me to not worry about.