P5B Deluxe only sees 3GB RAM?

[LintMan]

I'm bringing up my new system:
C2D E6700
Asus P5B Deluxe
Corsair Dominator 4x1GB DD2-800 TWIN2x2048-6400C4D

So everything goes fine with the first 2GB, and I install Vista, etc with no problems. And then I added the second pair of memory sticks, and the BIOS only shows me having 3008MB of RAM (seems like an odd number). I boot into Vista, and it shows 2.93GB of RAM. (Vista supports 4GB ram, so that's not the issue here).

So I take out one of the new sticks, and the BIOS still shows 3008MB. So I put that one back and remove the other, and it still shows 3008MB. So, basically, all I see is 3008MB, whether I have either of the single sticks or both inserted.

My MB is flashed to the 1004 BIOS.

Edit: On the Asus web site, I found an FAQ saying that the upper 1GB is used for PCI mappings, etc and for 64-bit operating systems, to enable advanced memory mapping on the north bridge chipset. I'm running 32-bit Vista, but I tried it, and the BIOS now shows all 4GB. Hooray - my MB isn't busted! But, when I boot into Vista, it now only finds 2GB. Blah. 32-bit Vista's supposed to support 4GB of RAM, isn't it?

 

[n7]

I doubt it.

I can't say for sure, but i would expect 32-bit Vista to have the same issues as XP in regards to running 4 GBs.

I hope someone who knows more jumps in here with more info for you though.

 

[Steve]

All 32-bit OSes support (2^32= 4GB) of address space.

You have that much address space in which to fit your RAM, as well as hardware, I/O and other subsystem (PCI, etc) addressing.

 

[LintMan]

Where were you guys when I was reading all those threads here stating the opposite (that Vista would support a full 4GB RAM, unlike XP)? Or the table in this article which states 4GB maximum RAM for 32-bit Vista.

I just found this thread over in the OS forum: here

It seems that a 32-bit OS can be capable of addressing more than 4GB of address space. (There's 36 bits of physical address, which something called PAE mode can access if an OS supports it. XP apparently did at one time, then removed it).

I also found this MS knowledgebase article which implies you can use PAE in Vista to get the full 4GB, but from the thread here, an unsourced quote by blurredvision states:

32bit Vista does by design not(!) use the full 4GB of physically installed
RAM. Technically it could use 4GB (by using PAE to access the memory remapped by
the mainboard above the 4GB address boundary). By a marketing design
decision all Windows Vista 32bit editions are limited to 4GB address space.
Vista Starter ist limited to 1GB. "This is based on marketing decisions and
cannot be cheated with the PAE-Kernel."

 

[keeleysam]

Why don't you just install 64-bit Vista?

 

[LintMan]

Two reasons:
1 - I just bought 32-bit Vista Ultimate OEM. It doesn't include the 64-bit version. Had I known the retail versions included both 32- and 64-bit, I likely would have gone retail for the flexibility. (I ordered the OEM before the retail version hit the stores and all the details were out)
2 - I'm not sure drivers and back compatibility are where I'd want them to be right now for x64. For example, I don't think nvidia has a WHQL signed 8800 video driver yet, whereas I can at least run their latest betas in x86.

 

[MTDEW]

I dont have a P5B mobo, but on my P5WDH it will do that with 4gb installed if you dont have the memory remap feature enabled in the bios.

Now thats to get the motherboard to see the full 4gb.

Windows is another story.

EDIT...
I just looked at some screenshots of the P5B bios , it does have Memory Remap Feature setting.
Its on the same page as your ram timings, enable that an the Board will see the full 4gb.

Now all you have to do is get windows to see it too.
Good luck with that, from what ive read, youy'll never get 32bit Os to see the full 4gb.
If you do find a way, please post it here...

 

[LintMan]

I did find the BIOS memory mapping feature on my MB, and it does show the full 4096MB when I use it, but Vista only reports 2GB in that case.

As for 4+ GB and 32-bit OS, it is possible, and some 32-bit OS's do support it (including XP formerly - see the MS article I linked above), but apparently MS chose not to support it in Vista.