Question Does the P350X have a design flaw?

[furglelover]

I recently bought 2 P350X Phanteks cases and started building two new PC's.

However I have come across a problem which occurs on both cases.
When fully connected my Samsung 860 Evo SSD disappears from the bios and in windows and, when the case is switched off, my NVdia GTX 970 Graphics card's fan spins up on and off constantly when the power is off.

The only way to stop the fan and get the SSD to reappear is to either disconnect the sata lead or the RGB lead to the motherboard that come from the case.

I theorised that there was feedback powering the grapihcs card so I used a multimetre and measured a 5V charge on the sata power even when the case was powered down. The voltage also disapears when I disconnect either the case's sata lead or RGB lead.

Below are the components I am using for the build.
I have also tried a different PSU with the same result.

Aorus Z390 AORUS PRO
Samsung Evo 970 NVME
Samsung Evo 680 SSD
Corsair CP-9020131-UK TXM PSU
2X 8GB G.SKILL F4-3000C16D-16GTZR
Intel Core i3-9100F

 

[extreme_noob]

I don't see how this would be an issue with the case...

 

[furglelover]

I was sceptical myself until I tried a second brand new motherboard, the Aorus Z390 AORUS ULTRA, with the same result. Unless Aoros board's are incompatible but Phanteks own website doesn't think so, it lists both as compatible.

 

[extreme_noob]

I was sceptical myself until I tried a second brand new motherboard, the Aorus Z390 AORUS ULTRA, with the same result. Unless Aoros board's are incompatible but Phanteks own website doesn't think so, it lists both as compatible.

Hmm. Maybe try using a separate cable for the case and drive instead of daisy chaining?