I did the move in stages.
First I bench tested the new build with a linux usb boot drive.
Then I moved my boot drive to the new SSD and made sure it booted in the old system and windows still activated.
Then I swapped the boards out.
I had some issues getting the mbr disk over to gpt first. So I put the new ssd in and used a windows usb install to create a windows install on it but didn't finish it. I really just wanted it partitioned correctly as macrium reflect doesn't seem to have an easy mbr to gpt converter thing. Seem mini partition wizard does but I don't have a license for that. So once it was partitioned correctly I moved over the two partitions from the main drive. I'm not really sure what the @500MB one is for or if I should have copied that one. But after doing that it wouldn't boot. error code 0xC0000225. I found some instructions online
for repairing BCD and winload.efi file for UEFI device. You basically use diskpart to assign a drive letter (Z) to the EFI partition. Then bcdboot c:\windows /s Z: /f ALL. to copy the files over. That fixed the problem but I had two windows entries in the boot menu. I used msconfig to remove the incorrect one.
And it turns out I never enabled the xmp profile for my old system in the bios.
Once it booted with UEFI enabled and a gpt disk, I then swapped the board.
It worked first boot, yay. Made sure to enable the xmp profile this time on the new MB. Windows activated after a bit. It first said servers unavailable and then it let me reactivate.
I then wanted to get the bios updated and was going to use gigabytes's windows app. I tried to install app center and the PC crashed with page fault in non paged area. Uh oh. Continued to do that right after login on restarts. Booted fine in safe mode. I updated the bios from the bios directly. Then it booted fine. There were some notes in the latest bios update about system stability. I removed all the intel software and drivers. I installed the amd drivers. Ran cinebench for 30 minutes and it got up to 90C. That is concerning. I used the stock thermal pad on the stock cooler. I'm considering other coolers but as it is a small 3U type case, they need to be like 110mm. But I'll likely never push it that hard in actual use. I ran memtest86 overnight and all good. So I assume those faults were either that software or some driver or the bios.
Coolers I've identified are Noctua NH-D9L and Thermalright Silver Soul 110. But they are both a bit pricey for this budget build (Board was 39.99, cpu 119.99, ram was 84.99). I might just replace the thermal paste and call it a day.
One annoying thing is it seems to default the display to the HDMI one vs DVI for booting and going into the bios. I couldn't figure out anywhere in the bios to tell it which display to use first or as primary. I use the DVI as my primary.