I have a Gigabyte ep45-ud3p and was running Corsair 2x2GB 6400. Recently bought (2) 2x2GB Corsair 8500 and with all 4 sticks in, my screen will not turn on and sometimes even does the reboot loop after a few seconds. I got it working with 2 sticks and played around with the voltage a lil bit and currently have it set at 2.0. Supposedly they run at 2.1 but when i change it to 2.1 I get the same problems. Any ideas on how I need to set the voltage or what I can do to get this working. Im really hoping its not a bad slot. Any ideas or help is really appreciated. Thanks
Run memtest on each individual stick (plugging them in one at a time) and see if they have any problems
Also you will want to set the voltages to 2.1 and manually set the timings/speed to the given specifications. If your sticks passed memtest but still wont boot at the specified voltages/speed/timings you may have to lower the timings a bit.
If you bought the two pairs of sticks at different times, they are almost certainly NOT quite the same. Filling up all the RAM slots sometimes causes problems, especially with overclocked RAM like yours. Sometimes, boosting the memory controller voltage a notch (MCH) can help. Corsair has an excellent support web site at houseofhelp.com -- I'd go there with your situation.