Question Trying to get an ARC B580 to run on an i5-8400 & ASRock Z370 Extreme4

[Apexpulse]

Hey, so I updated my BIOS to the latest BIOS version 4.21 Beta which specifically says "Adds support for C.A.M. (Clever Access Memory)" I googled how to enable it because it wasn't immediately obvious, but I got it enabled but I still can't boot. It posts, then goes to a blank black screen with what looks like white single white underscore somewhere in the middle, and then reboots. Any ideas? Is it even possible to get it running on this old of a CPU? Specs below:

CPU: i5-8400 @ Stock Clocks
RAM: Ballistix 8GB 2400MHz 16-16-16-39 1.2V X.M.P. Enabled (BLS4G4D240FSB.8FBD)
MB: ASRock Z370 Extreme4 4.21 Beta BIOS Version
COOL: ID-COOLING SE-214-XT
GPU: ASRock Challenger ARC B580
SSD: Samsung 970 EVO 1TB
PSU: Powerspec CW 650 Watt 80 Plus GOLD ATX Semi-Modular Power Supply

BTW The PC boots fine if I take the GPU out and also my B580 works fine on my other PC with the 9800X3D.

 

[Lutfij]

PSU: Powerspec CW 650 Watt 80 Plus GOLD ATX Semi-Modular Power Supply
How old is the PSU in your build? What did the P{SU power prior to the ASRock Challenger ARC B580?

If the BIOS was recently flashed, did you clear the CMOS and see if that helped bring the system to output display with the discrete GPU? Speaking of displays, did you drop the card onto the lower PCIe slot and seen if that changes anything? Is CSM enabled on your motherboard(even though you need it disabled in BIOS to gain access to C.A.M)?

 

[Apexpulse]

the psu is brand new. this is a hodgepodge of my old pc where i bought new parts to make up a backup pc, the psu i bought 1 month ago for it. i have not tried clearing the cmos or tried installing in a different pcie slot, will try both of these. and yes i did turn csm back on after enabling cam. thanks for the suggestions

 

[thestryker]

If it's posting it almost seems like there's some sort of initialization problem. It would be worth going into the BIOS and checking to make sure all of the expected devices are showing up there. Unfortunately I'm very unfamiliar with ASRock BIOS setup so I'm not sure where exactly you'd find the PCIe devices in there.

One of the important settings for ReBar functionality is "Above 4G decoding" being enabled, though from what I gather the card should still work without ReBar just not well.

That's about all I can think of which hasn't already been suggested. Oh I guess another thing would be does a different video card work correctly in this system?