|"Yes, I think I get the Xp 32 bit issue"|
"What I don't understand is why the bio tells me i have 4096m then after it starts it's bootup, before getting into Windows, it tells me 2536m"
No, obviously you still don't get it & probably didn't click on the link I supplied or any of the accompanying links. Maybe a copy/paste will help you to understand. Here's a portion of the explanation:
"Current operating systems, such as Microsoft® Windows® XP, can only use a maximum of 4 GB of address space; however, the amount of memory available to the operating system is less than 4 GB. Certain components within the computer require address space in the 4-GB range. Any address space reserved for these components cannot be used by computer memory.
The following components require memory address space:
- System ROM
- Integrated PCI devices, such as network connectors and SCSI controllers
- PCI cards
- Graphics card
- PCI Express cards (if applicable)
At start-up, the BIOS identifies the components that require address space. The BIOS dynamically calculates the amount of reserved address space required. The BIOS then subtracts the reserved address space from 4 GB to determine the amount of usable space.
If the total installed computer memory is less than the usable space, all installed computer memory is available for use only by the operating system.
If the total installed computer memory is equal to or greater than the usable address space, a small portion of installed memory is unavailable for use by the operating system."