F5o has been good with my Samsung Green 8GB kit. So far 2400 with 10-12-12-28 and 1.68v is 1000% coverage stable in HCI Memtest (DOS) version. I haven't tried lowering VDIMM yet and it is set as auto.
I have to have the slews at 4 to get past code 51, but though my above settings are stable, it looks like some more work is required to get the board to consistently POST without either doing the 15-03-15 loop or doing a 51. It sometimes needs a couple of loops to get the POST done and then it's rock solid.
I think there might be an issue with the tertiary timings. Some like tRRDR should only go up to 8 maximum I believe, but the UEFI lets me set them up to 16 and I don't think it's actually working as in Mem TweakIT, anything higher than 8 just either sticks at 8, or in the case of tRRDR, shows as 1 which causes stability issues. I couldn't work out why my settings were 1000% coverage stable in HCI Memtest, LinX stable with maximum memory, Memtest stable overnight but kept falling over within seconds in Prime blend. I found it was because I had set tRRDR at 9, and Mem TweakIT was showing that as 1. Lowered it to 8 in the UEFI, and not only does Mem TweakIT show that, but Prime blend is also rock solid now.
Only thing is that even though tRRDR is rock solid at 8, it causes more issues with POSTing, but eventually once it POSTs, I can reboot and start up without any POST issues, unless I go in and need to change anything, and then it is a matter of rebooting till it takes the settings.