Hardware issue?

[Curt Tresenriter]

I just put together a new system. AMD Phenom II AM3 X4 965 Black on an 
Asus M4A88TD-V EVO USB3 motherboard and some Mushkin DDR3 (2 x 2048) RAM.

Initially the installation went well (Natty) but things were acting 
flaky, mouse movement was delayed and/or jerky and L clicks were often 
without result until the button was clicked a third or fourth time.

I suspected the RAM, since these particular sticks (1333 MHz) were not 
on the Approved Vendor List. There are a few approved Mushkin modules 
that are rated at 1600 MHz but none at 1333, I just went with what the 
salesman recommended - also at that time I didn't know all the 
particulars of the board, only that it was highly rated for Linux use.

I ran memtest for a couple hours, RAM passed several tests with no 
errors and I decided to shut it down and try another install.

This time the machine just kept going to the BIOS setup page - without 
my hitting the Del key - six or seven times in a row. I'd save the 
changes and exit and on re-start I was back at the BIOS setup page again.
The next time it went to the Asus gate page, where you can choose to go 
to the boot sequence, Bios setup or Bios flash pages. I double checked 
that I had the correct drive in the first boot position and proceeded to 
save changes. Now it's going to the Asus gate page - as it should but 
only for a few seconds and ought to then proceed to  booting to the DVD 
and let me start the install - but it just hangs there. Tried this 
numerous times, last night and again this morning. Same result.

I was able, once, to get it to the boot seq by hitting Del and f8 
consecutively as soon as I heard the beep but it never showed the popup 
and just hung there.

I still suspect the RAM and am planning on returning the sticks and 
getting one of the brands and model numbers approved by Asus for the 
board, but I'm wondering if the motherboard itself could be the problem. 
I would need to exchange the board by Tuesday as I have one week before 
I'll have to deal with an Asus RMA if I decide to exchange it.

I did also try clearing the CMOS - first by moving the jumper to pins 2 
and 3. Since that seemed to do no good, per the manual, I then removed 
the CMOS battery and then moved the jumper. This also produced no 
noticeable result.
Since I'm only using two sticks of RAM (and they are matched and a kit, 
not two separately packaged modules), I also tried putting them in the 
other two slots - A2 & B2, according to Asus either of the two 
configurations should work for dual channel operation.

Does this sound like the RAM is the most likely culprit?... or should I 
just exchange both RAM and mobo? Or maybe there is some other 
possibility or something else I could try to narrow the problem down?
Could the processor itself be causing the problem?

Not sure what to do next.

Thanks for any input!