Hardware Memory Hole Remapping in the BIOS

[o_o]

I have Mach Speed MSNV-939 Motherboard and 4 sticks of Corsair Value Select 1 GB DDR Memory. Actually a few months ago one of these sticks went bad, and I replaced it with an identical module. Before that stick went bad, I could see about 3.2 GB RAM on Win XP Pro 32 bit. After the stick went bad, due to the configuration of the motherboard, I was limited to 2 GB. When I got the new/replacement stick (same brand and model no), I cannot get more than 2 GB. I did attempt to go into the BIOS and reduce the DDR speed from Auto (or 166 MHz) to 100 MHz, but I still see only 2 GB in Windows. This Motherboard is limited to 4GB, and all along the BIOS shows the entire 4GB. Memtest also sees 4GB when booted using a USB after adding the replacement stick.

My Problem:
I attempted a fresh install of Windows XP, as well as (separately) Windows 7 on this machine. Both 32 bit. In both cases I can only get only 2GB in the Task Manager. In the Computer Properties though, Windows 7 shows 4 GB but in brackets it adds (2GB usable). These are both fresh installs with the default configuration (no startup flags etc.)

I then went into the BIOS and ENABLED H/W Memory Home Remapping. I did not change anything else. (DDR Speed was set to Auto).

Doing this resulted in 2.25 GB for both Widows XP and Windows 7. Why the extra 0.25GB? I thought for 32 Bit Windows, Remapping in the BIOS puts a large chunk of the RAM over the 4GB limit, so a 32 Bit OS would not see it. But here my experience is the opposite.

I’d appreciate any clues.
Thank you in advance,
O. O.

 

[razel]

You replaced with an identical stick but 'due to the configuration of the motherboard' you are limited to 2GB. I think this is the where you'd need to investigate. If the stick were identical, but you are now limited to 2GB, then something in your BIOS changed, otherwise the stick is not identical.

 

[C1]

Your not disclosing enough information about diagnostics. Are you using dual channel?

What happens when two modules only are used, an original module paired with the new one.

Create a table showing the results of testing the various modules/sticks :
- Single Channel:
+ Each stick individually
+ Two Sticks in pair (one original with one old) in primary slots

- Dual Channel
+ Two original sticks paired in primary slots
+ Two sticks, one original and the new one paired in primary slots

Depending on what has happened, expand the above testing to include suitable combinations including the secondary memory slots

You could have something as simple as two memory modules which wont pair when placed in the secondary memory, but might work in the primary slots.

Ensure that memory voltage is set at specification and if possible raise it one notch (lowest allowed fraction; eg, + 0.050 volt).

 

[o_o]

Dear razel & C1,

Thank you for responding. Sorry for the delay.

C1, yes you are correct, I have not exhaustively tested each stick of RAM. However all 4 sticks are recognized in the BIOS, in CUP-Z and in MemTest, and MemTest passes. If I boot the machine using Puppy Linux on a USB, I can see all 4GB in /proc/meminfo.

Now this is weird:

I thought Windows 32 bit (XP or 7), limits the memory to 4GB, and this includes the Graphic Cards, Network Cards, Sound Cards etc. So I decided to pull out as many cards as I could. I then decided to take out the battery of Motherboard for 10 mins (i.e. reset it for sure). I then booted up Windows XP which was previously showing me only 2 GB, and voila, I get 2.75GB!!!

Now the problem: If I restart the machine, then it goes back to 2 GB??? No other changes i.e. a simple restart.

I’m still looking for ideas if anyone has a clue.
Thanks again,
O. O.

 

[Z15CAM]

I can't say if this "Enable 4GB of memory on Vista" article applies to you but it may be worth a read: http://www.ocmodshop.com/enable-4gb-of-memory-on-vista/

I was able to use a Full 3GB on a GeForce GA-N7400 that only supported 3GB of DDR running Win7 32-Bit Ultimate and seems to me I had to tweak it out of her to do it. You can Tweek the Kernel to see over 4GB of Ram but all 32-Bit OS's will never use more the 3.4GB's

I also recall some older MB's having a Toggle in BIOS for Memory Mapping both 32 & 64-Bit OS's.

 

[o_o]

Thank you Z15CAM

I can't say if this "Enable 4GB of memory on Vista" article applies to you but it may be worth a read: http://www.ocmodshop.com/enable-4gb-of-memory-on-vista/

I was able to use a Full 3GB on a GeForce GA-N7400 that only supported 3GB of DDR running Win7 32-Bit Ultimate and seems to me I had to tweak it out of her to do it. You can Tweek the Kernel to see over 4GB of Ram but all 32-Bit OS's will never use more the 3.4GB's

Do you really think this is an OS issue? Initially after resetting the BIOS, I get a 2.75GB. Once I restart it, it goes back down to 2GB. Why does this happen?

I also recall some older MB's having a Toggle in BIOS for Memory Mapping both 32 & 64-Bit OS's.

Actually, my original/first post addressed this. It seems that memory mapping works differently in my case. Hence my question if this is the way it was supposed to be.

 

[jolancer]

dunno but i do believe 2 sticks of higher capacity always ran better than 4 sticks on those old mem controllers. my first guess would be they are not identical, even if they have the same model number the chips can differ. especialy since your ram is old, i would find it doubtful a replacement would be identical on value series ram.

If your bios has the ability i would look more closely at the Timing and volt settings than the speed seeing as its already at 166 deafult? thats pc2700 speed already... if its on T1, changing it to T2 alone maybe enough to stabilize the difference(if there is any between them).. mind you depending what you use the system for if, IF the only way you eventually get it working is lowering all the settings including ram bus speed, you'l have better performance with just 2gigs anyway.

 

[o_o]

Thank you jolancer.

dunno but i do believe 2 sticks of higher capacity always ran better than 4 sticks on those old mem controllers. my first guess would be they are not identical, even if they have the same model number the chips can differ. especialy since your ram is old, i would find it doubtful a replacement would be identical on value series ram.

I’m curious why do you think it might be a problem with the sticks if they ALWAYS work the first time I clear the CMOS? I am happy with 2.75GB, but not with 2GB. (Loading Optimized Defaults from the BIOS does not do the trick)