RAM usable 2.45 GB inspite of 4.00GB

[s k maitra]

My PC configuration is-----Processor: intel Core i5 4th gen, RAM 4GB, ROM 500GB, NVIDIA 2GB in-biult graphics, OS= Windows 8.1

Until my OS was 8.1 32-bit, it showed only 2.45 GB usable RAM.. but after upgradation of 32- bit to 64-bit, it is showing accurate 4GB Ram. Why did this occur?

 

[basroil]

That's because you had a 2GB video card, motherboard, etc. You NEED 64bit OS to see all 4GB of a 4GB system even without dedicated graphics memory, throw in dedicated graphics and it's even worse.

There are actual programming reasons for it, but you shouldn't worry about them too much now that you have 64bit.