Only 3GB Usable and Slowing Down my System (64-bit OS)

Haven't done the 7 thing myself, but this should still be available.

In MSConfig - Boot.ini - Advanced Options. Make sure nothing in MaxMem

Thanks for the replies. Actually I've read on memory remapping and checked to see if its an option in my bios and its not. Also, 4gb is shown in my memory count at post.

My motherboard is rather old, but i was hoping to not have to build another computer in a year or so.

Yes, changing the MaxMem may be for debugging, but that doesn't prevent it from limiting the OS memory. We've solved several problems like this after finding a setting there.

Thanks tcsenter. Seems like there's boards so old that they don't have the re-mapping, then older ones that have it, then newer ones that don't even bother with it again.

Manual has no info on BIOS - simply shows the main screen and you're on your own.

This motherboard has a strange DRAM slot configuration. It has 2 DDR slots and 2 DDR2 slots! Seen something like that mentioned before but hadn't run across it.

yep yep, that's what I meant. I don't think anyone ever needs it set the other way anymore - no boards sold to support Win95 or OS/2 anymore.

Just like few boards use RAM this big!

There might of course be some exceptions and then it depends on how you define "newer". G31/P31 supports memory remapping very well.

If I should add a bit. 945GC only supports 4GB address space, so a remapping function would be rather pointless.

From the specs:

The (G)MCH supports 64 GB (36 bit) of host address space

The reclaim base/reclaim limit registers remap logical accesses bound for addresses above 4 GB onto physical addresses that fall within DRAM.

what the exact amount of ram it shows in the post? cause i am sure its not saying its 3GB even. it might be reserving some of the ram for other devices on the board.

but it could be a design limitation of the board anyway because the specs say it only supports a max of 4GB but maybe it only supports like 3.5GB.

I was quoting the chipset specs. Yes, the chipset only supports 4GB RAM, but the address space is larger than that. There is a difference between RAM and address space.

Have you not read the specs? There are several pages explaining its memory remap feature. 945G has a 32bit interface to the CPU, P31 has a 36bit interface.

Lets take a board as an example: P5KPL-VM
If you go to bios setup, you will find a memory remap function right there.

It seems from the discussion above that the roadblock in you being able to use more than 3GBs of RAM isn't due to the OS being 32-bit or 64-bit, but to the design of most boards using this chipset.

Adding RAM that works properly will never slow down your system. Your system should run faster and better in Win7 than in Vista - but that's just a guess. But no idea if it'll run better in Win7 64-bit, for which it was clearly not designed, or in Vista 32-bit. The best OS might be Win7 32-bit for you.

So there's no reason that having 4GBs (3GB) in your system will actually run slower than 2GBs. It should run Vista faster with the 4GBs - even if it only addresses 3GBs.

Again, I don't think having the memory is slowing down your system. I'd stick with the Vista and save the Win7 64-bit for your new hardware. Of course, if you can sell or return the 4GBs of RAM now it will fund a portion of an upgrade to a newer MB, RAM and CPU - any money spent on old hardware is basically down the drain at all times unless it makes a visible improvement in your system now.

I'll have to take your word for it. The last 10 persons with a G31/P31 based mobo that I've seen posting inquiries about why their system addressed less than ~3.5GB RAM with 64-bit OS did not have any setting for memory remapping in their BIOS.

Its not the chipset memory limit that would cause the slowdown. But a buggy BIOS that wasn't properly setting-up things like MTRR settings when 4GB is populated sure could. Seen it before.

I Goolged my problem and found this thread. I'm having the same problem as the original poster. There are few differences. After I switched from 32bit Vista to 64bit Windows 7, I added 2 more Corsair XMS2 sticks to the 2 I already had. The 2 new memory sticks are a couple of years newer and look different even though they are the same specs. But with them installed my system is quirky. Sometimes everything runs smoothly and other times everything runs extremely slow and clunky. I removed the 2 newer ram chips and the system runs great. My system is a Gateway GM5424 that I purchased March of 2007. I changed many of the components. My system setup now is:

Intel (Stoughton) G965 Motherboard
Intel Core 2 Duo E6700 Processor
Corsair Twin2X2048-6400C4 memory
Antec Truepower Trio 650w Ver. 2.2
BFG GeForce 8800GT OC

Could it be that the newer ram chips are not compatible with the older pair or is it the motherboard can't handle the 4megs.

Thank you very much for the reply. It may not be necessary now but here are the specs:

CORSAIR XMS2 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory - Retail.
5-5-5-15 2.1v

Both the first and second pair are identical. I purchased both sets from Amazon about 2 years apart. I didn't get the second set until after I switched from Windows Vista 32 bit to Windows 7 64bit. I know that you wouldn't get the full advantage of 4gb on a 32bit setup so I didn't bother with getting 4gb until I installed Windows 7. Anyway after I posted here I found someone with the same problem on another forum. It was suggested that they increase the size of their paging file. I tried that and also put the paging file on a second hard drive. All have been well for the few days since. I'm surprised it was such a simple solution, if it holds up. I was sure it was some sort of hardware conflict. Thanks again and take care.

~eddie