Solution: The issue I was facing wasn’t a power issue. My Vega 56 not POSTing was due to BIOS auto settings (on both B450 and Z77) that only adversely affected Vega specifically. Manually disabling integrated graphics while in external GPU mode allowed to POST on B450. Had this running off the same lead with 150% power limit without issue (besides fan noise).
Basically, I got this new GPU (MSI Vega 56 Air Boost) and can’t get it to post on my computer. I want to confirm it’s not a power supply issue prior to RMA-ing it, but I don’t have a spare PSU nor do have the modular cables to confirm. I have a Rosewill Tachyon 650. The PCI-E lead I do have terminates in a dual 6+2 pin layout, which fits the 2x 8 pin required by the Vega GPU; the question is can it deliver through a single cable? The output, per Legit Reviews: [email protected], [email protected], [email protected], [email protected], [email protected]
I did check on two platforms: My original 2500k with ASRock Z77 Pro4-M - but would not POST: no POST beeps, no display signal. Bought a whole new platform (Ryzen 5 2400G, MSI B450M Gaming mobo) and still won’t POST, no beep, and no display signal, but the Debug LED indicates GPU issue. The system boots fine with integrated graphics and old R9 380X (single 8 pin).