Biostar

The symptom is caused by BIOS option SATA/IDE combined mode set to "Enabled".
According to AMD chipset specification, when you set SATA/IDE combined mode to "Enabled", SATA5&6 will be set to IDE mode.
You can set the option "SATA/IDE combined mode" to "Disable" for all SATA port to run with AHCI mode.

Intel P55/H55 chipset will not be able to support 8GB (double side) or 4GB (single side) size memory module.

It's due to chipset support limitation.

Intel uses DVMT (Dynamic Video Memory Technology) for on-booard graphic share memory.
It will share system's on-board memory for graphic share memory, but keep most of system memory size for usage.

Please check VGA memory size refer to Intel's FAQ.
http://www.intel.com/support/graphics/sb/CS-033984.htm

With BIOS default setting, graphic memory only use 64MB physical memory, but total DVMT memory size is 1696MB under Windows. System memory availible size is 3.88GB out of 4GB.

Currently socket 1155 motherboard with Intel B75 / H61 / H67 / H77 / P67 / Z68 / Z75 / Z77 chipset will support single side 4GB memory module.

Older socket 1156 and 775 mainboard will not be able to support it.

Due to on-board CPU limitation, A68I-350 Deluxe will not be able to support dual channel memory.

It will only support single channel memory.

Win7 64 bit will support SATA in AHCI mode.

So it will be best to change DVD ROM or DVD disk for finish the Windows installation process.

The maximum DDR3 speed for Intel G2020 CPU will be 1333 MHz.

So B75MU3B will support up to DDR3 1333 speed due to CPU specification limitation.

Please update SSD firmware v1.0 from Samsung website.

It will be able to fix the RAID problem.

http://www.samsung.com/us/support/owners/product/MZ-7TD250KW

1. Set Volume Control Options to HDMI® or SPDIF output.

2. Install 3rd party DVD player like PowerDVD.

3. Set PowerDVD Audio setting for SPDIF as primary output.

4. Adjust DVD or Blu-Ray's audio playback setting to DTS output.

5. DTS sound will be able to playback through DTS supported amplifier.

Yes, it will support by Ubuntu 12.1.