Hmm... This is very weird... If what GeneO wrote is true, then I should only have less than 3GB available to my OS (which is NOT the case). I know that the chipset (or the memory controller in particular) needs to have the ability to access all of those memory banks that it's connected to, but Wow... This topic is very interesting indeed.
If you read my system specs, I have 2 display adapters, a GTX285 1GB and 8800 512MB... Those two alone should reduce my 4GB installed RAM to 2.5GB available to the system... But currently, all 4GB RAM is usable, even back in WinXP 32bit, I have around 3GB RAM available (with 4x1GB sticks installed). This is still not counting all other devices that are installed on my PCI(e) bus. As for display adapter's local RAM, it's a whole different device, and it uses different access method, and is addressed differently. In case you're wondering by this fact, the simple question would be: can you access the graphic adapter's local cache as a "real" RAM and have CPU a complete control over it? As if it's an extension of main memory...? Hint: display adapters have firmware that governs it self, we can say that it's more like a BIOS for display adapters, thus you can't really access it's RAM directly, not with that firmware in the way.
But enough... What to remember is, before you put in more RAM to your computer, you should ALWAYS read what's the maximum RAM size supported by your motherboard's memory controller. This is the main requirement of how many memory banks the memory controller can access/control. Regarding memory mapping feature, this is perquisite with the chipset's ability to address it's RAM. If it supports more than 4GB, it will have memory mapping feature.
The next factor is the OS. To be able to use all of those RAM, we need an OS that have enough address space to use all of those RAM.
https://www.sevenforums.com/general-d...omparison.html have all the info.
As for the OP, as stated by rich64, Darician, Zeplash, stormy13, and many others (and my self): Stick with 3GB if you're planning on using 32bit OS, upgrade to 4GB if you wish to use 64bit OS... As simple as that.
zzz2496
Edit: I'm not sure if I read the thread starter correctly... The OP have a physical display adapter card, which is the same as me. After that, I re-read GeneO's post once more. If I read it correctly, maybe GeneO means display adapter that's embedded on the motherboard's chipset (an onboard display adapter). If this is the case, then we are not talking about the same thing. Onboard display adapter's local cache uses main RAM, this is true, but the OP's are using a dedicated display adapter card, which doesn't share it's local cache with main RAM...