64-bit FreeNAS not accepting all of my RAM...

[clownphish]

This issue raised its ugly head again after my latest upgrade from 9.2.1 to FreeNAS-9.2.1.2-RELEASE-x64. It's annoying, but now I think I have the process down to a fine art! Here it is (hopefully it helps someone else)

1. Upgrade & reboot. System Information shows 4GB of RAM while the BIOS detects all 8GB (looking at dmesg, real memory= 8GB, avail memory =4GB as per my earlier post)
2. Shutdown, take out RAM from slot 1. Reboot. System sees 4GB of RAM
3. Shutdown, take out RAM from slot 2 and re-install the RAM from slot 1. System sees 4GB of RAM
4. Shutdown, insert both sticks of RAM and boot. System sees full 8GB.

Subsequent reboots are fine (I suspect until I perform an upgrade). I don't understand this behaviour and why it only happens on upgrade but at least I know a work around. I'd be interested if anyone else has any suggestions on how to fix this (other than changing the motherboard!) or if they have the same issue / solution? My motherboard is an Asus E45M1-I Deluxe (AMD E-450 processor)