I am running Win 8.1 32 bit on a MSI P35 Neo with 4 gb of RAM. Been looking at upgrades for RAM and it would be about £120 to get a matched set of 8gb RAM or there abouts. But I will be sticking to 32 bit OS even if I upgrade to Win 10 as most of the drivers for my peripherals are included on 32 bit but not 64 bit OS. I have spoke to one of the driver guys at MS and there will be no support on 64 bit for my peripherals in the future.
So that leaves me with an expensive RAM upgrade, but would the 32 bit OS see anymore than 4gb so 8 gb would be a waste?
IMHO, a waste of money. It won't be usable on a 32 bit OS. Your likely not using all of the 4 gig you have now. 32 bit Windows can only address 4 gig. Anything used by add-in cards will subtrack from that usable space. for example if your video card has onboard RAM, that has to be mapped into that 4 gig address space. What is left will be used to made your RAM. If your video card has say 1 gig of dedicated RAM onboard you'll only be able to use 3 gig of your motherboards RAM. Adding more RAM to the motherboard will not change this. You have to go 64 bit to address more.
All 32 bit versions of Windows are restricted to a maximum of 4 GB RAM as part of the license agreement and this is enforced by the kernel. All RAM above 4 GB will be ignored by the OS and unavailable to any application. The extra 4 GB RAM could be used by some RAMDisk products but the benefit to performance would be limited and not worth the cost. It would be more cost effective to install the OS on an SSD.
I echo what's been said so far and also want to reiterate what LMiller7 said, if your system doesn't already have an ssd in it (none are listed in your system specs), your money will be much better spent adding an ssd than putting in additional RAM.
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