What it the history on this board? Have you had a working installation of Win98 on it before? Can you try installing with an IDE drive to see if it is a CF card/adapter issue? These sorts of issues seem to often crop up with CF cards and IDE adapters, hopefully someone who has experience with them can chime in.

It's a "new" purchase and the seller claimed he tested it prior to sending, provided some photos of the test bench, good rating. From this and the fact it runs Windows 2000 normally I guess everything is OK.
I've tried Windows 95B on it and got to Windows Protection error due to the CPU speed. I did not try to patch but moved on to w2k next, which just installed normally and runs fine.

The use case for this comp is to run late 90s to early 00s FPS, both Windows and DOS, software rendered. I thought about Win98 and setting up its DOS environment because that's something I don't actually do normally, so to try it out. These games do support win2k and normally I dual boot with DOS so I'll just go the usual way here.

For me one of most important things is silence so no HDD, I mean I can and will see if that was the cause, but in the end it will be CF.

Apart from dosbench testing and Quake under DOS at 1024x768 I also ran Quake 2 on win2k, I believe the board and RAM are ok.