Proble with RAM OC on DP67BG

[ajinta]

Hello everone. I am having a trouble with oveclocking my memory and i hope you can help me.
But first things first here are my specs :

DP67BG Intel extreme motherboard
Core I5 2500k (oveclocked to 5Ghz stable)
16 gb G.Skill F3-10666CL7D-8GBXH ( two kits of total 4 stics of ram)
http://www.gskill.com/products.php?index=346
coller master v8 CPU coller
2x MSI NGTX560ti 2GD5 graphic cards in SLI
OCZ vertex 2 SSD 60gb
1x 500 hdd
1x640 hdd
LC power arkangel pover suply ( 850w 74amp)
Extended ATX InWin Maelstrom case

The computer in working wery vell an stable with cpu on 5 ghz.
But the problem is that I cant change setting of ram at all only thing that works is XMP profile that loads defaul settings which are 7-7-7-21 1333mhz.
but problem is that if I only change from XMP to user settin and leave everything on default it is already enough to fail to start.
It is strange that system fails to bot with the exactly the same original setting on user setting option, but works with the same setteng under XMP without a problem.
This is my first Intel build so please tell me if I have to change something else in the BIOS to practicly allow me do do any memory OC.

Thank you all.

 

[jsc]

I'd say, "Don't bother."

Overclocking RAM in an Intel system (can't speak for AMD) adds little, if any, extra performance.