Please help with memory issue

I have 2 CMX6GX3M3A2000C9(I can't find anything anywhere about this RAM kit. Is it a new kit or just not bought often?) (Corsair XMS DDR3 2000 9-9-9-24) kits on a Asus P6X58D Premium Motherboard with a Intel Core i7-930 Overclocked stable to 4.0GHz ( this is my first time overclocking) and I can't use the XMP profile since I'm using 12GB. So since this is my first time overclocking and in the DRAM timings part of the bios is about 30 options(not quite but close) I'm wondering what settings I should mess with and what is the absolute tightest (Stable) timings that I might be able to get. I want to run the RAM as close to DDR3 2000 speeds as I can unless it isn't worth it. I could really use your guy's advice here on if I should go for DDR3 2000ish speeds (and if so what timings(and which settings to mess with)) or go closer to DDR3 1600 and get tighter timings? Also Which ever way you think I should go with it please include what my QPI/DRAM voltage should be for the Speed/timing(it took me long enough to get my overclock stable as is since this is my first time and I don't want to have to guess what I should set them at and guess wrong lol). Thank you all in advance for any guidance you can provide for me. I choose to ask here because I know that tom's hardware poster's are very knowledgeable and willing to help anyone who genuinely needs help (you got to help now that I put that in right? lol).