Can you tell me what Patriot kit you have. 5-5-5-15 covers:
Viper 2 (PV224G8500ELKB)
Viper (PVS24G8500ELKR2 and PVS22G8500ELK)
Blade (PDC24G8500ELKR2 and PDC22G8500ELK)
Viper series have tall heatspreaders, Blade are standard height.
Patriot RAM can be a bit finicky with some boards, more often than not it because of the higher than usual voltage they need to run. The fact that the system runs with one stick would lead me to believe that the voltage may be the culprit along with the "RAS# Active time" setting which the board has set at 12 when it should be 15 (i.e. the timing is to tight for the RAM to operate in complete stability). Don't worry about the sub timings ( ...-3-52-6-3-3) unless you plan to tweak the RAM for maximum performance.
For a base guide on your RAM timings in your BIOS...
Boot into your BIOS. Select the second tab "A.I.Tweaker"
Set PCIE Frequency to 100 (if not already set)
Set DRAM Frequency to DDR3-1066 (if not already set)
Set DRAM Command rate to 2T (if not already set)
Set DRAM Timing Control to Manual
Note the string of timings following "Pri.Information" on the next line-they should be the same as the settings you are about to input.
Set CAS# Frequency to 5 DRAM Clocks
Set RAS# to CAS# Delay to 5 DRAM Clocks
Set RAS# Precharge to 5 DRAM Clocks
Set RAS# Active time to
15 DRAM Clocks
leave the rest of the timings on Auto for now and move down the page until you get to..
DRAM Voltage ....type in
2.10 <<<<<<NOTE BELOW
Hit F10 to save and exit
NOTE DRAM voltage is a
minimum of 2.1v for any of the Patriot RAM kits I listed, but the kits whose model number ends in "ELK" are rated to 2.1-2.3v and depending on chipset (yours being P35) that could possibly mean a slight voltage bump is required (2.15-2.35). Be aware that 2.35v is the absolute maximum safe limit for DDR2 voltage.
If you post back with the kit model number I can be more precise in the settings you will need. I would recommend that you download
Memset if, either you cant locate a model number, or the RAM requires some subtimings to be tweaked. There is a screenshot of Memset 4.0 that I posted in another thread
here. I use the program to obtain the settings already embedded into the RAM, but the program is touted primarily as a method of tweaking settings while in an OS enviroment- I DO NOT RECOMMEND THIS. Always better to change settings through the BIOS and then run Memtest86+ as Archean has suggested.