Maximum RAM on p945pm chipset (Napa platform)

How much of the 4gb that you installed on your laptop can you actually use? I'm looking for users who have 4gb installed but cannot use it all. I might put 4gb in mine, but it depends on whether I think I can get 3.5gb or not.

I'm just trying to figure out how much RAM your 945pm based laptops can handle. As far as I know, all C2D laptops that were introduced before Santa-Rosa have this chipset. It has a 32bit memory controller and therefore cannot access 4gb fully. It has to reserve addressing space for integrated peripherals, the video card and stuff like that. Most I've heard is that many of these laptops either get 3gb or 3.5gb usable memory.

So guys, spit it out if you have one, or have a friend who has one

 

no,it wont access full 4 gb!

 

Actually, If you used a 64bit OS, you would have all 4gb (not counting the vid card's reserved space) The more annoying part is finding a Merom that will let you use a 64bit OS properly and still be Socket M...

Otherwise your bottleneck is the 3.3gb of 32bit computing... as for worth it? I doubt it.

 

Are you saying that with a Merom (T7200 in my case) on the 945pm and Vista 64, I could be using 3.75gb?

Edit: my laptop has x1600 with 256mb of dedicated RAM

 

Well I just bought and installed 4gb, and my bios only shows 2944 mb, using bios 208t00. It could be that another bios leaves more usable RAM. Just a heads up for owners of Asus F3ja's or similar laptops

 

Well you should still be able to access all 4GB under 32bit Linux, it's just M$ that acts a little differently (although it too can be tweaked a little especially for Server and Vista).

Weird about the BIOS, sounds like their limit because the chipset should support to the 4GB.

 

The chipset has a 32bit memory controller, which can address 4gb of memory. However, it doesn't support memory remapping (unlike the Santa Rosa chipset; the 965), so all the addresses that are mapped to devices like my graphics card and stuff cannot be used to address the memory itself. I'm pretty sure ASUS could squeeze out a bit more usable memory if they'd bother, but they won't.

 

It (the 945) does have PAE support so it can still address beyond the 3.5, and of course it's limited to the resources already allocated, however it can still address the full 4GB even if it dedicates some of it elsewhere. Do you really think it's using 1GB for that? Depends on the OS and apps/use as to whether it's worth trying to add/force PAE support to their OS. For most users it's not worth the headache, because it causes more problems than it solves.

Forcing it in XP causes major slowdowns and instability due to software compatability issues only Server and patched Vista with properly supported drivers/software work well enough for it to be worth it IMO.

However that doesn't explain the BIOS other than the artificial limit since it should SEE the entire amount before it's allocated/addressed by the OS.