Dual channel not working

[krismedic]

Hello, I recently installed some new memory (2x2gb ddr2 pc2 8500 1066mhz Geil Black Dragon) on my mainboard (msi k9a2 platinum amd790fx) and for some reason, they're running in single channel mode. I'm positive that i've used the right slots as i replaced 2x2gb of different brand ddr with mis-matched timings that ran fine in dual channel. Even so, i experimented with different slots but stil no joy. I tested both geil sticks and they boot just fine individually. When both sticks are installed, sysem info shows only 2gb of available memory. Everest notes both sticks but only shows 2gb also. Both cpu-z and amd overdrive show 4gb of available memory installed in single channel mode. The system has now become unstable, games will run temporarily but always crash quite quickly. i have experimented with running memory at mainboard defaut of 1.8volts and at geil's recommended 2.2volts and it's still unstable. Please help, i'm trying to learn as much as i can but i need expert advice.

krisMedicine

 

[alcattle]

You should always use the voltage the vendor reccomends, surprized they work on stock voltage (1.8)

 

[jitpublisher]

Couple of things we need to know to accurately help you out.
What processor, what video card, and what OS?
Without knowing these details, it is all just speculation.

 

[krismedic]

Couple of things we need to know to accurately help you out.
What processor, what video card, and what OS?
Without knowing these details, it is all just speculation.

I've just installed a Phenom 2 940 quad @3ghz a few days before i got the memory. I've got 2, powercolor hd4870's in crossfirex, and
i'm running windows 7 ultimate beta 64bit (which by and large ithink is pretty good).
I built this rig myself but i'm a novice pretty much. The whole thing worked great until i tried to replace my mis-matched ddr2.

Thanks for the time guys.