I've 4GB RAM installed on my board (Colorful, Phoenix award BIOS, PCIEX graphic adapter). The BIOS & OS report 3.4GB or so (cpu-z identifies the entire 4GB). I've googled and found there should be a memory remapping option somewhere in the BIOS, but was unable to locate it anywhere on my machine. Any clue will be appreciated.
If your OS is 32bit (and I suspect it is) it can't "see" the whole 4GB of RAM because it has a maximum addressable space of 4GB and in it it has to reserve addresses for I/O ports, graphic memory (which I suspect is 512MB in your case), etc.
During POST you should see the amount of RAM that is reported. Is it 4GB?
I don't know where you're reading 3.4 in BIOS, and that remapping option, even if it exists, I don't know how beneficial it is.
Anyway, I have 4GB of RAM. In Windows XP 32bit I see 3.5GB, and in Windows 7 64bit I see 4GB. In both cases, I think it is more than enough memory.
forever, I believe the mem remapping was an option on some older BIOSs, not seen that much now. I believe that dropping Win 95/98 support made it un-needed, but not sure.
As PaCanc said, the BIOS should be showing the full 4GBs. As should the info on the POST when the computer boots. It's only 32-bit Windows that will only see 3.4 or so. It's the limit of addressable RAM allowed by 32-bit OS.
So you're just fine and enjoying all the RAM you can. And your money for 4GBs isn't wasted - your system runs much faster than if you had 2GBs and 3GBs would be slower due to losing dual-channel memory mode.
Thank you for answering. My graphic adapter has 1GB RAM, and the exact amount of memory reported by the BIOS after POST is 3406784K. I use 32bit Ubuntu 9.04 which reports 3.2GB. Would switching to 64bit OS let me use the entire 4G's? Not that it's critical - I can live with those 3G+, but still...
Actually, all I have to do is download Ubuntu 64 Live CD and test it. Will report here when I'm done.
I'm with you gamerk - if the BIOS/POST is really reporting 3.4 then there's an issue.
forever - you said "memory reported by the BIOS after POST is 3406784K". Do you mean that this is the max count displayed by the memory test during POST? Did you enter the BIOS and see this number? Or is this a number reported by some program within Windows?
What motherboard/chipset do you have? It might not even be possible to use all of it with a 64bit OS. Linux has PAE support, so you can also address >4G with your 32bit Linux.
The board is a Colorful C.P31AK 2.0 1005 (http://en.colorful.cn/Product/Specific.aspx?guid=f316cc...). However, just tried this: I disabled Quick POST in BIOS and let him actually count installed RAM. It ran for a few minutes, and reboots when the count reaches 2089xxxKB. Could it be bad memory chip? I don't recall having crashes during heavy memory usage (I ran a game that consumes more then 2GB).