Motherboard +12V broken sensor or should I be concerned?

[xollextor]

During idle, the MB's +12V stays flat and stable at exactly 12.000V (also in BIOS), it also stays flat and stable at 12.000V even under CPU load (i7-10700KF stock) which would draw around 130W.

Where it gets weird is when the GPU is under load (drawing 340W), the MB's 12.000V would drop as low as 11.424V and even spike at 11.328V which certainly is out of +/-5% spec.

However both the GPU 8-pin 12V sensors are at ~12.1V and never drop below 12V (RTX 3080)

Is the motherboard's 12V reading busted?

PSU: Corsair TX850M Gold
MB: ASROCK Z490 Phantom Gaming 4
CPU: i7-10700KF @ stock
GPU: RTX 3080

 

[Martin]

I believe the values are correct - both the mainboard and GPU PCIe sensor report a similar drop in voltage. Seems the mainboard +12V supply is not sufficient.

 

[xollextor]

I believe the values are correct - both the mainboard and GPU PCIe sensor report a similar drop in voltage. Seems the mainboard +12V supply is not sufficient.

So the PSU isn't the main problem? both motherboard and PSU are new as far as the retailer has told me, 2 months of usage so far.

What makes me believe it's a motherboard issue because both GPU's 8-pin 12V remain in between 12.000V and 12.116V even under both heavy GPU and CPU load, it's just the MB's 12V and GPU's PCIe's 12V which is connected directly to the motherboard and only drop under GPU load, not CPU. But I'm not an expert so I could be wrong.

I just hope this doesn't become a disaster or potential danger to my components in the long run, spiking at 11.328V doesn't sound safe but nothing I can do, so far the system is stable for now.