So, when the system boots up with the CPU on-die video (and monitor hooked up to it, not to the card) does the card still get detected and show up as a device in the system?
In case yes, something is wrong about the display handshake, or maybe the grounding/cabling/port is acting up or shot dead. I would try to attach ANOTHER display to it after the system is fully booted and see if it gets detected in different display ports.
In case not - GPU has to be diagnosed, likely a hardware issue. There are no further user-friendly troubleshooting steps that I would advise unless you are a tech...
Edit: forgot to ask, do you happen to have fast-boot enabled? If so, disable that first.
In this case the GPU is NOT detected in the BIOS, whether I put it in the PCIe x6 or x8 slot....or now confirmed even in other systems. I believe you're right that it is the GPU at this point.
Pascal is pretty touchy about voltage inputs and needs a solid 12V to start, which is an issue especially on systems with many components which have a high power-on current (HDDs , pumps, and similar stuff)... the way you describe it, it seems as if it has a handshake problem but the real reason would be power-up sequence.
To verify, take a separate PSU, hook it up to the card (use a powered riser if you have one) ground the inverted-enable pin with a clip, (pin 16 to either 15 or 17), let it run for a sec and only then power up the PC.
I would try it on the TS card too but he mentioned swapping out a PSU so... I assume it handles the current delta well enough.
P.S Make sure to have a common ground between the PSUs.
Yes I've done quite a lot of testing, along with switching out to a brand new Corsair PSU, and as of yesterday I tried the card in TWO other systems and both exhibited the same issue and the card not detected at boot.
I get why the card isnt detected, as its not even spinning up, Its for sure getting power though. Thank you for your suggestions. And I suppose the issue is as you mentioned a handshake issue of some sort, as when it goes successfully the card runs no problem.
Thank you for the suggestions vov4ik. Just wanted to acknowledge your reply, i appreciate it. I won't go into it further here not to hijack op's thread. System runs fine however, it's not an issue i could be bothered diagnosing really.
System is all fine outside of GPU (and now has a new PSU 😂)...Ive run Intel Burn Test, Prime 95 3dmark (inc. CPU), memtest.....only other thing I can think of is BIOS hates the GPU for some reason...some real Gigabyte on Gigabyte crime if you ask me.
So want to thank everyone for their help here, Im trying to keep my son positive. I've reached out to Gigabyte and they have agreed if I want I can do an RMA. Going by the serial the card is still under warranty (you can tell by reading the date in the serial number) but without a receipt they will not be able to replace the card if it cant be repaired. I suppose at this point that is my only option.