I have 2 sticks of 2GB RAM. I added a single 4GB stick. My PC is showing only 6GB.

[trustymutsi]

Here are the specs.

mobo: Asrock Z75 Pro3

Link to the manual: http://asrock.pc.cdn.bitgravity.com/Manual/Z75%20Pro3.pdf

RAM:

G.SKILL 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1333 (PC3 10600)

Kingston 4GB (4096 MB) RAM - DDR3-1333 - 240 Pin - KVR1333D3N9/4G SFF

No matter what order I put them in, this is what happens:

If I put in 2 2GB sticks and the 1 4GB stick, it only sees 1 of the 2GB sticks and the 1 4GB stick. Doesn't matter what order I put them in the slots. If all 3 are in, it will always see the 4GB stick, and not see one of the 2GB sticks.

If I remove the 4GB stick, the BIOS now sees the 2 2GB sticks.

BUT... the BIOS WILL recognize any of these stick by themselves (I only insert one stick in one slot.)

Is it possible that I don't have enough power for all 3 sticks?

Thanks very much for any help!

UPDATE: Someone on Reddit found a source that says my mobo can only handle 2 or 4 sticks. Not 3. Thanks for all the feedback!

 

[Jwpanz]

Look in page 20 of your manual. It states that if 3 slots are populate that it will not activate the dual channel mode. This leads me to think your motherboard has compatibility issues with 3 sticks. It also states that you need to use identical sticks of RAM whereas you are mixing brands and sizes.

In short, I think you’re hitting a compatibility wall and not a power issue. This is why you can see the sticks by themselves or with just two inserted but not all three.

If you can track down an identical set of RAM as your 2x2GB set then you should be golden.

 

[trustymutsi]

Look in page 20 of your manual. It states that if 3 slots are populate that it will not activate the dual channel mode. This leads me to think your motherboard has compatibility issues with 3 sticks. It also states that you need to use identical sticks of RAM whereas you are mixing brands and sizes.

In short, I think you’re hitting a compatibility wall and not a power issue. This is why you can see the sticks by themselves or with just two inserted but not all three.

If you can track down an identical set of RAM as your 2x2GB set then you should be golden.

My 2x2GB are perfectly identical. The 4GB stick is the different brand and size. Strangely enough, my BIOS sees the 4GB and ONE of the 2GB sticks, but never sees the 3rd stick (which is an exact match of the other 2GB stick)

 

[Jwpanz]

Ya, this goes back to my point about compatability. Your motherboard just may not be able to run all three sticks since one is different.

 

[Calvin7]

Memory manufacturers guarantee memory in the form it is sold in and not by matching up identical part numbers.