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I have Windows 7 on a gaming PC. I have an Asus Rampage Formula 3 motherboard with 24 GB of RAM. When I go to system properties, it shows that I have 24 GB of RAM, but it says in parenthesis that only 16 GB are available to use. How do I get it to be able to use all 24 GB if needed?

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Out of sheer curiosity. Why on earth do you need 24 Gigs of RAM on an entertainment PC? A server I could see, especially a Host for Virtual machines, or for SQL or something, but just a regular PC? You can't POSSIBLY use anywhere near 16GB let alone 24. Can you? – Paperlantern Mar 27 '12 at 13:01
@Paperlantern: Who says you need it? RAM is cheap so you may as well fill all the slots. You can use it to cache 1080p movies in RAM. – Zan Lynx Mar 27 '12 at 15:55
@ZanLynx: But then you are at least using it (sort of, even a full dual layer movie would be what? 8GB? Throw in 2 or 3 in use at most from OS and other programs and you are barely using half of 24GB). This is what I was referring to, personally I couldn't come up with a use for that much memory outside of running a few VMs (which I do regularly, I butt up against the 8GB I have all the time), but for JUST a gaming PC... 24GB seems a little overkill. I agree it is cheap so why not, but even if its $10, why spend it if its just going to sit empty for the life of the PC? – Paperlantern Mar 27 '12 at 16:01
Drive caching. The system automatically uses RAM as a drive cache when it's not being used by applications. 20GB of caching is pretty damn nice when you're looking at installed game footprints of 10-15GB. The game will not need to wait for drive access more than once for any particular file. – Myrddin Emrys Mar 27 '12 at 17:29
@Paperlantern Even if I didn't run VMs, when I bought my RAM it was as expensive to get 8GB of RAM than it was to get 16. I remember 24 wasn't that much more expensive either. – gparent Mar 27 '12 at 17:43

It sounds like you are running Home Premium, which has a limit of 16 GB. You will need to upgrade to Professional, Enterprise or Ultimate to get access to the remaining 8 GB.

See Physical Memory Limits: Windows 7.

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Thank you for the help – Brandon Mar 27 '12 at 13:25
Your welcome. Don't forget to click the little check mark to select it as the accept answer :) – Melikoth Mar 27 '12 at 14:37
Ugly artificial limitation! – UncleZeiv Mar 27 '12 at 17:49
If there wasn't a limitation, there often wouldn't be a reason to move to Server. – EKW Mar 27 '12 at 20:00
@Melikoth And he forgets! – Ismael Mar 27 '12 at 20:47

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