My new memory modules (Crucial part code: CT25664BA1339) do not appear to be compatible with my computer system (Alienware Aurora ALX).
I installed the new memory modules in to the 3 remaining slots giving a total of 12 GB (i.e. 6 x 2 GB). I ensured that the modules were fully seated with both clips in place; although I did notice that the new modules are 2-3mm higher than the old ones.
When the computer is switched on the fan starts on maximum speed and the hard disk drive light is on constant. The computer does not boot, the BIOS screen does not display; no error messages are displayed and no alarm beeps are sounded to indicate what the problem may be.
I switched off the computer, uninstalled the memory and my computer is now operating correctly again.
Before ordering this new memory I downloaded and ran the CrucialUKScan compatibility checker to ensure that I ordered the correct memory. It does not specifically list this memory module (Crucial part code: CT25664BA1339) in the list of compatible upgrades (inc. Crucial part code: CT1026793) but the specification of these two modules is exactly the same i.e.:
I reseated the modules and replaced the old modules with the new ones. The computer beeped 3 times, booted and reported: MCH using DDR3-1333MHz. Warning! Overclocking failed. System restored to default setting. 4088MB OK.
So now it only has the new modules in but is only using 4GB instead of 6GB. Does this indicate a compatibility (timing) problem between the old and new modules or are the new modules faulty?
I reinstalled all 6 memory modules and rebooted. Windows 7 reports 12.0 GB (7.99 GB usable); I found other people reporting this problem and tried the following solution: BIOS only reports 8 GB but DIMM1 to DIMM6 have no errors shown - so I loaded default BIOS settings (mostly Auto) and rebooted but this has not changed memory detection.
I think I'm nearly there... what should I try now / more BIOS changes?
When you had only the new modules in (6GB total), it only recognized 4GB. This is a huge indicator. One of the modules could be bad. Since now, when you put all the modules in, you only see 8GB. This could be because 1 of your 3 memory channels has the bad module in it. The bad module could be keeping the 3rd memory channel from functioning altogether.
First thing to try-
The way you can find the bad module is:
1) remove all the RAM.
2) Use only 1 stick of the new RAM in the bank 0 (or 1 depending on your motherboard) of the first memory channel.
3) Start the PC
If it boots to Windows, the module is probably good. Repeat this 2 more times with the other 2 RAM modules. Find out which module keeps the PC from booting. If one of the modules keeps the PC from booting, you can probably conclude it's a bad stick and you should start the RMA process immediately with Crucial.
On the other hand, it could be a problem with the motherboard. If you determine each of your new RAM sticks allows your PC to boot, you may need to upgrade the BIOS to the latest release. I know some motherboards had issues recognizing memory in all banks. Upgrading the motherboard to the latest BIOS was usually the fix (considering all RAM modules are functional).
Second thing to try - upgrade your BIOS (I'd do this anyhow after you determine whether or not you have a bad RAM module).