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April 22nd, 2014 05:00
OptiPlex 745 -- Help with Added RAM
I have an OptiPlex 745 with 1 GB of RAM (2 x 512MB) of original memory. I added 4 GB (2 x 2GB) of RAM this weekend. The computer sees the 5 GB of RAM but says that it only has 3 GB of usable memory. Why is this? I made sure that the added memory was the same type, and I put them in slots 1 and 3.
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speedstep
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April 22nd, 2014 07:00
32 Bit windows 7 is the issue.
32-bit Windows has an address space of 4GB. Part of that is used by system BIOSes and graphics memory.
With a 256MB graphics card about 3.3-3.5GB of RAM can be addressed and used, assuming you have 4GB fitted.
If you fit a graphics card with 1GB of memory only about 2.6-3.0GB of the RAM would be addressable and usable.
Your Ram is fine and its working.
When you put 8 gigs of ram in a 745 you do not get the full 8 gigs due to ram being used for the INTEL video. This does not come back when you add a video card.
The usable memory may be less than the installed memory on Windows 7-based computers
http://support.microsoft.com/kb/978610
Windows 7 Physical Memory Limits
http://msdn.microsoft.com/en-us/library/aa366778(VS.85).aspx
The system memory that is reported in the System Information dialog box in Windows Vista
is less than you expect if 4 GB of RAM is installed (Windows 7 is the same) http://support.microsoft.com/kb/929605
Mark Valetti
6 Posts
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April 22nd, 2014 07:00
speedstep
11 Legend
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47K Posts
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April 22nd, 2014 07:00
There are 2 factors.
1 is that some of the ram is stolen for video.
2 Any more than 3 gigs of ram depends on 32 bit or 64 bit OS and CPU.
Mark Valetti
6 Posts
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April 22nd, 2014 07:00