They should be running in dual-channel mode w/all 4 DIMMs filled.
How are you determining the speed the RAM is running at? CPU-Z and PC Wizard 2007 are both decent programs to determine such things, and are free.
You should also read this post on speeds and timings: http://www.tomshardware.com/forum/200599-30-memory-nooo...
Just raise the speed of the memory in the Bios.
On my socket 939 when I installed 4 sticks of memory the speed dropped from 400 to 333. I raised it to 400 without any problems.
Run memtest86+ and prime95 to be extra sure.
i have this same board. in order for the RAM to work in dual channel mode, all 4 have to be identical. And even, for some reason that i am not clear on, it will only run at 333. I think there is that BIOS tweak you can do, I just haven't bothered. But since you listed the timings and they were different for each pair, it won't run in dual channel mode.
Ignore pogsnet's post. DDR200 is a speed, not a standard, so of course it exists. There are many reasons why RAM rated at DDR400 might run at DDR333 speed. Anyway, just go ahead and adjust the speed in the BIOS, kavok, and see what happens.
I went into my BIOS and checked the speed - or whatever. The highest the menu would let me go is 250Mhz. I selected 250Mhz and restarted. My POST gave one long continuous beep with no display, reset, repeat etc..
I had to pop out the CMOS batter to get it to boot.