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I've installed Corsair Vengeance CMZ16GX3M2A1600C10, 2x8GB, DDR3-1600, PC3-12800, CL10, DIMM and my BIOS picks up that there is 16GB, Windows says there is 16GB, CPU-z says there is 16GB. But it only says I can use 4.99GB out of 16GB.

Motherboard is P55-GD65 (MS-7583)

Supports four unbuffered DIMM of 1.5 Volt DDR3 1066/1333/1600*/2000*/2133* (OC) DRAM, 16GB Max



(Above screenshot specifies that I am on a System type: 64-bit OS)



Microsoft says that the physical memory limit on a 64 bit win7 professional operating system is 192GB.

Dxdiag Run Command


BIOS Screenshot #1


BIOS Screenshot #2


Why is my OS limiting me to just over a quarter of the available memory? is there anyway to increase it?

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migrated from Oct 3 '12 at 3:48

This question came from our site for system and network administrators.

Have you checked BIOS to make sure it's not reserving any of it for CPU or something? What motherboard or laptop are you using? Can you update question with this info please? – Sponge Bob Oct 3 '12 at 3:55
where abouts in the BIOs would I check if any memory is being reserved for the CPU? – Killrawr Oct 3 '12 at 3:56
Hmmm, I'm not exactly sure - it's going to change a lot from computer to computer. Can you try to google your specific computer, or maybe just poke around for a few minutes. – Sponge Bob Oct 3 '12 at 3:57
Please run memtest, located here, Also play around with the DIMM slots and see if there are any problems with the motherboard. Update your question with your results thanks. – AlanTuring Oct 3 '12 at 4:12
up vote 0 down vote accepted

I fixed it on my windows 7 PC by simply going into msconfig -> boot -> advanced options. And increasing the maximum memory and then running a reboot.

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