A bit of an odd one this - I should point out I bought this machine from ebay a few years back - really happy with it but I run a lot of Hyper-Vs so I needed some more RAM. I had 4 sticks of G.SKILL 4GB PC4-24000 DDR4-3000 RAM (part number F4-3000C15Q-16GVR - I should point out I haven't built a PC for 20 years so am behind on hardware). Anyway, needed to get 64GB so went to crucial, used their scanner and was sent 4 x 16GB DDR4-3200 (Part number CT16G4DFD832A). Anyway, booted up and couldn't get to the BIOS and had 5 long beeps. Went through lots of things with their support (CMOS BIOS reset, BIOS upgrade etc), but he gave up and told me to send them back for a refund. Anyway, decide to have 1 more crack at it; left all the original RAM in, but then started replacing them one by one. Weirdly that started working and got to slots 2, 3 & 4 filled with the 16GB sticks, and just slot 1 with the original but it seems no matter I do, I can't get slot 1 to take a 16GB stick without it beeping. Its not the stick as if I swap it for another that works in slot 2, 3 or 4, it does the same thing. Any ideas?