hum I had my laptops motherboard replaced by Asus last month... Not sure that really was the issue in the end as it wasn't booting with 5600 RAM after bios update but now it's back from RMA, everything's disabled in BIOS but RAM still stuck at 4800. ...

my scar 18 RAM is stuck at 4800 since that update, are your's fine?  

thanks for that! How much ram do you have?

I'm not sure 64gb 5600 is possible anywhere though. Could you try just one stick?

new bios Version 309 on the 18, no new ram speed?