I purchased an ASUS P5Q Pro Turbo LGA 775 Intel P45 ATX Intel Motherboard. I have (4) four 1gigs DDR2 memory modules. The motherboard excepts two gigs of this memory, but when I try to install the (2) two remaining modules the computer refuse to boot. I tried installing them one at a time but still, the computer will not boot. The memory modules are none descript and I can't locate the information on them. Can this be a memory issue or shoud I be looking at some component. The board boots fine with only two modules and word relatively good. I have the Intel core duo E8400 processor with an Ati Radeon 5770 and a good dell monitor. Still the display is fuzzy.
If you have run memtest86+ on boot for each stick individually and had no errors, then you know you are working with 4 sticks of good memory. If you have not run memtest86+, you should, just to know all 4 sticks are good. If they are not, and you only have one good set, no further action is needed - use the good ones.
OK, so you have two sets of 2 sticks of good RAM. Boot with one set of RAM and take GhislanG's advice to get the specs from CPU-Z. Use CPU-Z's SPD tab to find the mfr, speed, latencies, and voltage settings (write them down). Then remove those sticks, firmly seat the other two sticks, get their specs from CPU-Z SPD tab. If the the 2 sets of RAM do not have matching voltage settings, or are not very close, within ~.5v, choose the set of RAM you want to use and don't try to add the others to your board.
-- Re-start the computer, enter the BIOS (Ai-Tweaker), set the RAM latencies to the highest values (of the 2 sets of sticks) you saw in CPU-Z's SPD tab.
-- Enter the BIOS voltage settings for the RAM, enter the higher voltage.
-- Save the BIOS settings, unplug the power cord, ground yourself, firmly seat the two other sticks of RAM.
-- Re-power. If it boots to the OS, you should be good, if, not, you can re-start the machine, enter the BIOS and increase the NorthBridge voltage setting in .02v intervals, saving and re-booting after each increase - do not exceed 1.90v here (see manual, page 76). Many boards are tuned to 2 sticks of RAM by default, and require a little more juice to boot with all four RAM slots filled.
This should get you to your OS, where you can run your favorite stability test programs.
CPU-Z reads your hardware and displays info on your CPU, RAM, and motherboard. This is the link to CPU-Z. Install and run this first so you can identify your RAM mfr., size, frequency, and latencies. After you install it, open it, and you will see the tabs I mentioned above.
memtest86+ is a diagnostic testing tool for RAM. You run memtest with the RAM operating within its frequency and voltage specifications. If the RAM is bad, memtest86+ will show errors, if memtest shows no errors, you have good RAM. The webpage has instructions for using it. A lot of folks say it works best when you boot to memtest from POST, using a CD, USB stick, or floppy because the operating system doesn't get in the way - remember Windows takes some memory to run. Memory that is restricted by Windows cannot be tested by memtest while the OS is running. This is the link to memtest86+.