Q: I'm trying to increase the general gaming performance of my PC for memory hungry Flight Sim X. I see the cheapest and easiest way is to upgrade my system from 2gb of Ram to 4gb. I have heard that as XP is a 32bit operating system it is limited to 4GB of ram. Allowance has to be also given to other hardware memory. I have a x1900xt Graphics card with 512mb. So if it true then if I upgraded would I only be able to use 3.5mb of ram when there is physically 4gb there? Would I notice any considerable performance increase in my games from just 1.5 gb? Is there anyway around this apart from changing my operating system? Basic system specs are 2.2Ghz Dual Core Processor 2gb Ram x1950xt 512mb Graphics card Win XP Pro SP3 32bit
A: You best option is to upgrade to 3GB (if your motherboard has 4 DIMM slots and allows this) 2GB in one bank, 1GB in the other bank. Yes, you'll see improvement going from 2gb to 3gb in memory-hungry applications like Photoshop. You trade off dual-channel mode for an extra 1gb of RAM and less frequent swapping to disk. With Flight Sim X, I'm not sure but I'd guess keeping more scenery in memory and avoiding swapping may outweigh dual-channel mode. The 4gb addressable limit isn't specific to XP, it's the maximum for any 32-bit operating system (2^32, it's just math). In 32-bit Windows, 3gb is available to programs and memory above the 3gb mark is used by the Windows kernel. To use more than 4gb, you'd need a 64-bit OS. The inability to use roughly the last 512mb of address space beween 3.5-4gb is because that area is where hardware like system ROM, video cards, PCI resources etc get mapped. The exact amount taken varies from system to system based upon the hardware. So there's no point in having RAM occupy that area- in fact having RAM there does slow things down, compared to a 3GB system where it's unoccupied. it's just like the old DOS days on the IBM PC (when the maximum addressable memory was 1GB but only 640K was usable)