Need some help tuning CMX4GX3M1A1333C9 for my Mobo

Hi, first time posting to this forum -- I was searching around and some folks said that this was a great place to get help with RAM issues.

Some background:

I recently bought a barebones kit 2x4GB CMX4GX3M1A1333C9 RAM. I initially installed Ubuntu 11.10 64-bit and seemed to be running great with the default settings (Award BIOS ver. FB, I believe it is the latest). BIOS shows RAM runnign at the recommended 1.5V. I upgraded to the new Ubuntu 12.04 LTS and started having video driver issues, which I thought I had cleared up. I began experiencing frequent system freeze/crashes, and numerous catastrophic program crashes. Watching video and using Firefox would frequently result in hangs/freezes or crashes. I was at my wits' end treating it as a video driver issue, and decided to reinstall 11.10 since that was my last stable configuration. However, multiple install media (disc and USB) failed to install on multiple tries, giving i/o errors at various stages. HDD checked out OK, and optical drive worked to run Live CD and create a USB startup disk, but I kept getting i/o errors stating it was likely a hardware issue.

I ran memtest86+ with both RAM sticks installed, and it kicked an error first and then crashed completely (black screen with colored vertical bars). I removed one stick of RAM, and ran memtest again, and it completed a pass with no errors. I then was able to install Ubuntu 11.10 64-bit from the same media I tried previously, and it installed smoothly with no errors. I upgraded from there to 12.04 with no issues or hangs. Today I tested each RAM stick individually, in each of the two slots (4 tests in total) and they each completed a pass successfully with no errors. I then attempted to run memtest with both sticks installed, and it again kicked an error but did not crash. I let it run for two passes, which it completed, but had an error during each pass (both times the error occurred during test 1, at locations 00141500698 - 5141.0MB and 00130d00250 - 4877.0MB respectively).

This leads me to believe that the RAM sticks are good, and that it is possibly a voltage or PSU issue. The RAM is CMX4GX3M1A1333C9 1333MHz 4GB 9-9-9-24 1.50V ver8.16, purchased as I said as a part of a barebones kit so they are an identical pair.

My Questions:

1. Would it help to raise the DDR3 voltage to 1.6V or 1.7V incrementally and memtest?

2. Is my 450W PSU too weak for my current system (listed below), and would an upgrade to say 600W or 650W be suggested?

3. Are there any other recommended tweaks such as to the timing? Currently it is set to SPD defaults.

Sorry for the verbosity but I am a bit in the woods when it comes to this sort of thing being my first PC build, and I wanted to include any info that may be useful for anyone willing to offer advice. Thanks in advance, I appreciate any help or advice you can offer!