Maybe this doesn't belong in the beginners section, but I have limited experience with either OS or the hardware. I've had this XP / Ubuntu 12.04LTS dual boot setup on a partitioned hard drive for some time, and it has worked fine. (I use XP for a CAD application, and Ubuntu for everything else.) I heard that even 32 bit Ubuntu can take advantage of more than 4GB RAM, so I dropped another IDENTICAL 4GB in the two empty slots on my motherboard.
The BIOS detected the 8GB. I booted XP, and the box promptly crashed. I restarted into Ubuntu, and the Unity desktop appeared, but froze. For some reason I wondered if my 550W power supply is the issue. I restarted and entered the BIOS to see what I could find. I took a chance and selected "automatic droop adjust" for the RAM voltage. I saved the setting, and rebooted into Ubuntu. This time I got to the desktop and it runs fine, but the launcher only has a third of the icons I put there. I restarted my machine, and booted into MEMTEST86+. I'm 77% through the tests with no errors found yet.
My machine has a 550 Watt power supply, a Gigabyte EP-45-UD3P motherboard, 8 GB 1066 Mhz DDR2 RAM, a 250 GB hard drive, and a GT9800 - 512MB video card. Is the problem the supply? if so, what size do I need? How do I fix the launcher? Is there something I must do to enable the 8 GB RAM support? For instance, should I just install a 64Bit version over my 32 bit installation? And I hate to ask this, but what about Windows? It should just ignore the RAM upgrade, right?
Thanks for your time.