HP Z420 wont post with XFX RX580

[CannaraX]

Already tried, makes it even worst, no POST after changing to UEFI.

I was able to try Slot 5 with a PCIe Riser and there it works but not nearly perfect, often get "Suprise Link Down"-Error.

I think the motherboard has a issue with PCIe 3.0, Slot 2 completely broken and Slot 5 partialy broken, on PCIe 2.0 its working fine.

Too bad...

[SamirD]

Interesting.  I wonder if it is just that particular card if other PCIe 3.0 cards work.  Unfortunately, I don't know if others do or not.

[CannaraX]

Yes, other PCie 3.0 cards up to x8 (physically) are working fine, only card that utilize more than x8 physically are causing problems.

I also tried to limit the speed of Slot 2 and 5 to PCIe 3.0 x8 but that also does not change the problem, it has something to do with the physical connection.

[SamirD]

That's a bummer. 😞  I wonder if it is just that motherboard or an overall design issue?

[CannaraX · Accepted solution]

I would guess its the motherboard because i tested the card with a second Z420 (exactly the same revision) and there everything is working fine.

So sooner or later, if i want maximum perfomance, i will have to replace the motherboard...

[SamirD]

Ah bummer. 😞  Well, at least it isn't a systematic problem and you know the exact issue.  Thank you for posting the root cause!