Yeah I decided it's probably something related to it not being an Intel. There might be an updated BIOS for it around somewhere, but I don't think it's worth trying that. I might just get hold of an Intel 2/66 if I see one around 😀 Thanks again

Thanks for the advice 😀 On this occasion however I think I did it right. The 33 and 66Mhz both use the same jumper settings 😀

http://stason.org/TULARC/pc/motherboards/D/DI … -LPV-DECPC.html ^ Online manual

Oh I remember the pain... I thought I’d upgrade my 486 from a DX2/50 to a DX2/66 I had lying around. I changed the jumpers as shown below, but for some reason my bios is showing it as a DX4/100 which the PC doesn’t even support! It runs but won’t boot. Not only that but it won’t even turn on with …