I have bought the ASROCK Q1900B-ITX together with a Kingston RAM KVR1333D3S9/8G module.

My problems started at the very beginning when I installed a second module of RAM, a Kingston KVR1333D3S9/4G on the DDR_B1 slot. An error message appeared when Windows installation attempted to start for the first time saying:

"Your PC needs to restart.

Please hold down the power button.

Error Code: 0x0000001E

Parameters:

0xFFFFFFFFC0000005

0xFFFFF800FA16430E

0x0000000000000000

0xFFFFFFFFFFFFFFFF"

This error message usually appears on VMs that have not enabled the execution-bit feature on the bios, but in my case it has been enabled by default (google searched it myself).

This failure has been identified when i first attempted to install Windows (7, 8, 8.1) from an installation disc. After removing the 4GB ram module the system initialized normally and the installation was completed successfully. Windows updates where applied successfully. 

Now, If I try to install the 4GB module back at slot 2 (DDR_B1) windows keep failing to load and the system falls in a restart loop with the above error message or something similar to that as it goes really fast and its difficult to catch it. I understand that there might either be an incompatibility issue between the two modules of ram (which would be really weird since they are the same model but with only different size) or a problem with the motherboard and the second slot of RAM (DDR3_B1). I have replaced the 8G module with the 4G at slot 1 (DDR3_A1) and Windows boot normally. If I try to put the 8g module at slot 2 (DDR3_B1) while having the the 4G module on slot 1 (DDR3_A1) the system again fails to boot and falls on a restart loop (as windows fail to load).

I was wondering if anyone has ever experienced anything similar to this, or has the knowledge to provide some advice or directions to me as I really cant figure out a solution to this.