PC Processors

[Gregory1]

Ryzen 5 1600X CPU (what I was upgrading from)

ASrock B450 Gaming-ITX/ac motherboard.

BIOS version P4.81 (I've tried 4.80 and 5.20)

2 x 16GB 3200 Patriot memory 

Zotac mini GTX 1070 GPU

EVGA 750 G3 PSU

I thought it would be a straightforward upgrade. I originally flashed to the 4.80 BIOS.  I installed the 5800X3D, and nothing. 

The GPU fan would spin and nothing else. The CPU cooler would get warm though.

One time I got all the fans spinning and thought it came alive, but I've not been able to replicate that since.  It still didn't POST but it felt like some progress at the time.

I tried the more recent BIOS revisions, and the 4.81 beta.  I tried one stick of RAM, I tried one stick in both slots.  I bought new RAM (the old stuff was Corsair LPX and wasn't stable at XMP anyway).  I tried clearing CMOS after flashing the BIOS.  I tried removing chipset drivers.  I tried updating chipset drivers.  I tried different BIOS revisions.  I tried removing all video and AMD drivers. I

I get beeps from a connected internal speaker with the RAM out.

The 1600X posts and boots every time.  The new 5800X3D does not.  I've gone round and round trying everything I can think of, and trying anything I can find on forums with a similar issue and found nothing that helped.

I also tried a second 5800X3D, thinking it must have been a faulty one, only for it to also not POST.

I'm out of possible solutions and exhausted with frustration.  I hope someone has some ideas or can help.

[MADZyren · Accepted solution]

Motherboards VRM might not be sufficient.

ITX has little room for VRM in the first place. Sounds like it could be an older boards and VRMs do wear out over time, especially if they run hot. Also while I know high end Asrocks receive decent reviews, the few casesI know where a motherboard of DYI computer has broken over time, have been Asrock. I generally prefer Asus motherboards, while admit they are a bit expensive compared to competition.

So, sorry, but I believe you need a new motherboard. 

EDIT: I think I would get mATX or ATX to get more options and cheaper prices, also get mATX/ATX compatible case and transfer hardware to new motherboard and case. PSU compatibility might be an issue.

[Gregory1]

Thanks for your reply.  I did consider the possibility of some fault with the VRM or even the PSU. It would have to be a very specifically technical fault that's beyond my scope to diagnose.  The system with the old Ryzen is really stable, and as far as I can tell, the 5800X3D runs at about the same or lower voltages and with only slightly more power draw under load -- which wouldn't be happening at POST anyway. 

I will be getting a new motherboard when the one I want is in stock later this week, and see how that goes.