First
I'm a long time reader of tom's but first time poster.  It's a wonderful website.
 
I recently purchased an ASUS p5e ddr2 1200 Motherboard and 1g x2 patriot ddr2 1200 ram.  The computer would not post with both sticks in, but it would post with one stick in (didn't matter which stick).  After some digging I discovered ASUS QVL that says it should work with (OZC, kingston, and corsair).  My question is does the manufacturer really matter?  Is all ddr2 1200 spec ram not made the same?  Any help would be gladly appreciated.
 
Thanks

Your BIOS is likely defaulting the RAM's voltage to 1.8v., not enough voltage to run two DIMMS rated at 1200MHz.  In BIOS, set the RAM voltage to RAM manufacturer specifications or bump up the RAM voltage to 2.0-2.1v.  You might set the timings to specifications while you are at it.
 
Download and installCPUZ to check your RAM frequency and timings:
 
  http://www.cpuid.com/cpuz.php

I have a similar board - I didnt have booting problems but I wasnt seeing all of the installed memory only half - there is a setting in the advanced section of the bios for the north bridge - enable memory remapping and see if that helps

No it's not all made the same. Some require different voltages than others, and some have better timings than others. You probably need to adjust voltages.

Thanks guys, just in case I did pick up some ram that was on ASUS QVL list so I have all my bases covered.  I'll do what you guys have recommended.