Super User is a question and answer site for computer enthusiasts and power users. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Possible Duplicate:
Is there way to enable 4 GB RAM in 32-bit Windows OS?

I have 12 gb ram triple set..but my OS doesn't see all 12 gb loads 4 gb board has x58 chipset.what's the problem?

share|improve this question

marked as duplicate by soandos, KronoS, Renan, Hello71, Mokubai Jul 17 '12 at 17:03

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

My first instinct is that you're not really running 64bit Windows 7.

Type "systeminfo" at a command prompt. About the 14th line down should be "System Type". That should say "x64-based PC". If not, you're not running 64-bit. Also, about 8 more lines down, you'll see "Total Physical Memory." Divide that number by 1,024 to see how many GB of RAM that your system actually sees.

share|improve this answer

I would suggest running Memtest and see if it is in fact the RAM. I have seen defective RAM slots on motherboards cause this. Take out all of the unnecessary RAM sticks and only boot with one stick. If the BIOS detects it and it boots to the OS, then power off and install the other stick in the next slot. If at anytime the OS or BIOS does not detect a RAM stick, move that stick into the first slot. Try different combinations of different sticks in each slot, in pairs and triplets. Make sure you document how each stick is positioned and in which slot, as it makes for easier troubleshooting down the line.

If possible, put the ram into another machine that accepts DDR3 and test each stick.

And if none of this works, you've got a defective motherboard or RAM.

share|improve this answer

Not the answer you're looking for? Browse other questions tagged .