missing ram

ok, here's the deal. my comp came with 512mbyte of ram originally , and i bought a 1 gbyte stick (centon, i think)around x-mas, then about january, i bought another gbyte stick (pny), so that gave me about 2.5 gbyte of ram. just last week, i purchased 2 gbyte of ram (pny, same as above). now when i took out the 512 ram (2 sticks, 256 mbyte each), and installed the 2 gbyte, my comp only sees 3.49 gbyte of ram. so, i think that maybe the new ram is messed up?, i then take out the 1st two sticks, and leave the last 2 that i bought, and moved 1 stick to slot #3. i boot it up and i have 2 gbyte. i then put back in the other 2 sticks (back to 4 gbyte), and boot into bios (it sees them all there), and exit out to boot into windows, and i'm back to 3.49 gbyte of ram. If it's a compatability issue (with 1 stick being different), then why would it recognize it before? also, the ram that i have (pny), isn't on the list, however according to pny, it will work.

this comp is:
HP Pavilion a 1214n
Pentium 4 processor (630?)

 

banks 2, and 4 show different , in that pre-charge all is not supported, whereas banks 1, and 2 do support this.
It might be a reason for it not showing as complete 4gig. The memories have slightly different properties.
Why not download Memtest , a free download from Majorgeeks downloads, and run the tests.
Also remember the Bios, will ( normally) be more accurate than any software program.

 

My understanding, is that the motherboard may be the limiting factor. I believe that the entire I/O space, and that includes RAM is mapped into a 4GB address space. This is just slightly less than 2^32 ( 2 raised to the power of 32 ). The missing RAM is "hidden" under the addressing scheme that the system uses to access your PCI bus, your video card ( AGP, PCIe etc.) as well as all peripheral ports, like USB, Parallel port. serial port, game port, and hard disks as well as sound and LAN support. It's still there, but you just can't use it directly. Until the Motherboard manufacturers re-tool a larger addressing space, this is going to be a problem for any 4GB RAM users.
.

 

Prometheos , thanks for that,
Sosaman, I hope you see what prometheos is saying, -There are some anomolies that will come up at times, and although your board will take 4g of Ram, Prometheos's explanation should show you why it shows less.