Showing Usable RAM 2.75GB while installed is 4GB

[electrosam]

Hello.
I have installed 2 modules of Gskill 2GB DDR31600MHz hence total memory is 4GB. But in the Properties of computer it is showing usable memory as 2.75GB. 512MB is assigned to on board ATI Graphics. So it should show 3.5GB usable memory.

Motherboard is Gigabyte GA-MA785GM-UD2H & Processor is AMD Phenom II X4 955.

Why this is happening ? Please help me out.

[noniinahui]

Re: Showing Usable RAM 2.75GB while installed is 4GB

Which operating system are you running ?
Only 64bit systems support 4gb of memory, with 32bit was 3,5gb max if I remember correctly.

Also, BIOS should display 4gb of RAM. If it does not, then it might be some issue with your motherboard.

[Geor9e]

Re: Showing Usable RAM 2.75GB while installed is 4GB

If using Windows 7; no matter what memory you allocate for video in the BIOS; windows will ignore it and take what it wants anyway.

[Chozo4]

Re: Showing Usable RAM 2.75GB while installed is 4GB

If using Windows 7; no matter what memory you allocate for video in the BIOS; windows will ignore it and take what it wants anyway.

*FACEPALM* Did I just seriously necro a thread? Sorry about that... T.T

(Original reply)
Check to see if you have the option for 'Memory Hole Remapping' available in your bios and if so, turn it ON. If you're using a 64bit version of windows, should have nothing more to do at this point.

Otherwise, if you're using Windows 2000, XP, Vista, 7 x86 (32bit) then you will be artificially limited to 4gb per licensing reasons, however - there are modifications to work around it which I will not mention as they alter system files. Personally, I've been using the 32bit version of Windows server which /can/ handle up to 64-128gb ram maximum but when I used XP-sp2, the next option gave me back a good 768mb of ram that was once 'unavailable'. The only other option is to use 'Gavottes Ramdisk Driver' in PAE-mode to reclaim 'lost' ram and any extra beyond 4gb to windows as a ram-based drive which you can instead relocate your pagefile onto (The article links to the newest version available). While one can just 'enable PAE' - that no longer works on its' own ever since they crippled it starting with Windows XP SP2 as a function to only access the NX bit and nothing more.

Further notes, it won't matter what you set shared memory for your onboard video to as any that ends up being 'lost' again to windows would be reclaimed by the ramdisk driver. This occurs because with memory remapping, the addresses once 'marked' for use by the devices on your system [video, networking, sound, etc] will instead be moved after your max installed memory and addressed directly to the hardware instead thus leaving the 'unaddressable ram' free again. Only reason windows doesn't use it if because of early reports back in windows 2000/XP-sp1 days of windows drivers causing issues with memory remapping and as such 'blocked off' from all use to avoid 'support calls'.Drivers are able to handle this without issue nowadays though so is no issue any longer for those willing to reuse it.