Well im hvaing trouble with installing my ocz sli memory in all 4 dimm slots i have tried all the ram in every slot and they all work its just the 4th slot doesnt work for some reason i am new this was my first build and i cant figure it out i am running xfx680ilt sli motherboard ultra 750watt power supply q6700 cpu 230gb sata when i use all 4 dimm slots the pc turns on and goes to a black screen and my exhaust fan doesnt start up anyone know of any ideas im having trouble looking at other threads so i cant read up as im on another pc cuz im waiting for my vista disc to come in the mail and this pc is slow trying to get the other up and running i hope i am posting in the right forum sorry if im not

Well here's one thing you could try; Install 3 of the sticks and go into the BIOS. Find the settings that control voltage going to the RAM and increase that number by 0.1 or 0.2. Then shutdown the computer and install the 4th RAM stick and attempt to boot again. It's also possible that your motherboard just isn't happy with running 4 sticks at a time, I've never had this happen to me but I've heard about it on a few occasions.

thanks for the help i looked in bios and voltage was only 1.8 for some reason ocz i hear takes 2.1 at least i changed voltage to 2.2 and still i get the same problem i wonder if there is any way to fix this

i also wonder if it could be the timings or something else i read in a forum where some vista patch and also some program that lets u change ur trfc setting or something excuse me if im wrong i appreciate any help tho

Yea adjusting the timings would be worth a shot, if they're say 4-4-4-12 by default then you could try 5-5-5-15 or higher. As far as adjusting the tRFC(Row Refresh Cycle Timing), normally that would be done through the BIOS as well, and it if you have that option then it might be worth increasing it a bit as well. Also, you can look into whether or not there's a BIOS update for your motherboard that fixes the problem. I tried looking on XFX's website but apparently you have to register before you can access their BIOS updates.

Well i would like to thank for the help i got the 4gbs working thank god and here was the solution i had to disable sli memory then change settings to 5-5-5-15 and change voltage to 2.2v i checked and got the bios update but i have no trfc option in my bios im glad its working and i would like to thank you very much!!!!!

Glad you got it running. Enjoy your first build!
=)