# 8GB RAM installed, only 4GB detected in BIOS, 8 in Windows (Only 3.99GB Usable)



## Perry| (Apr 15, 2008)

Hi,

I recently built my own PC and after installing all the components I noticed that from my 8GB of RAM installed, Windows is only using 3.99GB (Yes, I have a 64-bit OS) It says "8GB (3.99GB usable)" in the system info. However, in the bios it says 4040mb usable, nothing about 8gb. Running a memory info tool inside windows shows the specs of all the RAM installed in the rig however 2 of my 4 2gb sticks are not being used?

What I have tried:
Reseated RAM several times - the sticks all work, however I have noticed that the left hand side DIMMS nearest to the CPU are not displaying the RAM but Windows is able to detect it?

I read about a problem with 2.66ghz processors and 1600mhz ram in the motherboard booklet and it gave instructions on how to fix it in the bios. I did that, however no change.

Here are my specs.

Intel Core i5 750 2.66GHz Socket LGA1156 8MB L3 Cache
Asus P7P55 LX P55 Socket 1156 8 Channel Audio Out ATX Motherboard
Crucial 8GB (4x2GB) DDR3 1600MHz Ballistix Memory Kit CL8(8-8-8-24) 1.65V Unbuffered Non-ECC

Any ideas would be great, Thanks!


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## Tyree (May 10, 2009)

4GB of RAM is more than enough.
What shows when you remove two sticks?
Ballistix RAM is noted for having some problems.
A Bios update "may" help.


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## Perry| (Apr 15, 2008)

Well it depends where I remove them from. My DIMM slots are laid out like this.

A2 A1 B2 B1

I can have 2 sticks in B2 and B1 and I get 4GB, however if I put 2 sticks in A2 A1 I can't even boot. I have alternated the sticks so there is nothing wrong with them.

I have already updated to the latest BIOS version which in the release notes said it fixed memory compatibility, that got my hopes up....


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## Perry| (Apr 15, 2008)

Each slot to #4 shows exactly the same.


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## Wrench97 (May 10, 2008)

Try setting the ram speed down to 1333, like AMD the on chip memory controller on the i5/i7 chips limits XMP settings to 1 dimm per channel.


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## Perry| (Apr 15, 2008)

I set the ram speed down to 1066 and 1333Mhz still have the same problem.


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## Wrench97 (May 10, 2008)

At what voltage?


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## Perry| (Apr 15, 2008)

1.65v


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## Wrench97 (May 10, 2008)

Try setting it down to 1.5v if the bios is still picking up the EPP settings it will shut down 2 of the sticks. Or change your memory setting back to Auto.


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## Perry| (Apr 15, 2008)

I did both. Still nothing... The BIOS continues to say 4088mb


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## Wrench97 (May 10, 2008)

Clear the cmos and try, if you still only see 4gig I think it will be time to call Asus and talk about a possible Beta Bios update or RMA.


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