I'm trying to build my first computer and everything has gone well except for one thing, I can't get the RAM to run in dual channel. I tried returning the motherboard and ram to newegg, but the new ones I got have the exact same problem. The computer runs fine if I insert the RAM in a single channel configuration, but if I enter them in dual channel, I just get 3 long beeps and the computer fails to post. It seems too coincidental that with a new motherboard and new RAM, I would get the exact some problem... so the only remaining component I could think to blame is the CPU's memory controller. I don't have any other processors I can swap out to see if that fixes it, so the question I have now is whether or not is could be the CPU or am I wasting my time RMAing it? My current rig is as follows
CPU: AMD Phenom II X4 965 BE
Cooler: CoolerMaster Hyper 212 Plus
Power Supply: Corsair 750TX
Motherboard: Gigabyte GA-890GPA-UD3H
RAM: G.Skill 2x2GB F3-10666CL8D-4GBHK
Video Card: XFX HD-687A-ZNFC Radeon HD 6870
Hopefully I'm not missing any vital information
p.s. I've run through troubleshooting with gigabyte on updating the bios, changing timings, etc. with no success
1) That board has a rare feature called "built-in 128MB DDR3 SidePort memory" for 3D acceleration. I would try disabling that in BIOS and see if there could be a conflict with your main RAM.
2) To run dual channel mode on that board (just like on most boards) you have to put the ram in either the two blue slots or the two white slots. Make sure you are doing that as well.
Other than that, if the RAM appears on their QVL, it should run in dual channel mode. Considering that you have already changed out the board and ram once, then it could be that you just happened to hit on an incompatible match. You may have to get a different kind of ram- sorry to say.
I'll try disabling the sideport ram (or see if it is already disabled) when I get home this afternoon to see if that fixes it.
The blue slots on the motherboard are slots 1 and 3 and the white slots are 2 and 4. Each ram stick can successfully boot the computer by itself in either slot 1 or 2. I can also boot the computer successfully with 2 sticks in a single channel configuration of 1 and 2. If I try 1 and 3 or 2 and 4, the computer will not post.
I already changed RAM versions, although both models were made by G.Skill. The ones I have right now were specifically chosen off of the compatibility list on Gigabytes website for my motherboard. I guess I could try a different brand all together, but the fact that its on the list Gigabyte supplied makes me believe it's not an incompatibility.
If it were me at this point I would definitely RMA that CPU too. You might be right. But also check that it's not something else on the system. I'd remove everything including hard drives and DVD drives- and leave just power, ram, and GPU/CPU. Try that minimalist boot and see if it will post with a dual channel config.
Its possible that the settings in the memory's SPD register default settings are being more aggressive than they should be for dual channel mode. Often memory with improved CL specs are designed to run at a higher voltage (1.65V often... from 1.5V DDR3 stock voltage).
When in single channel mode... go into BIOS and either override SPD mode and pick very loose timings... or make sure the DDR3 voltage matches the spec voltage for your memory. I've had modules that required reduced timings when 4 modules are installed (in dual channel).
I'm less concerned with this... but also double check the speed rated for the QVL. They have different tables for different tested speeds. Stuff should still work... but its a possibility. I've seen more RAM and mobos go bad before CPUs... but its all possible. Good luck!