memory remap mobo, FUD or genuine concern?

[taltamir]

I have noticed it mentioned in a few (non reliable) places that some boards such as the ASRock H55M-Pro lack memory remap option in the BIOS and that it somehow causes 64bit OSes to "lose" some of their ram in 4+ GB settings... are the people who say that full of it or is there something to the warning?

Anand didn't mention anything about this in their review of the board so it sounds like FUD to me.

 

[taltamir]

nobody knows?

 

[Absolution75]

I've never even used a board where memory remap feature was available. I thought that feature was for 32bit OS's anyway? I think that whoever said that got 64bit confused with 32bit as I don't think its necessary.

Don't worry about it.

 

[taltamir]

People keep mentioning it in forums around the web, or product reviews...

for example in this thread here in anandtech: http://forums.anandtech.com/showthread.php?p=29938559#post29938559

It may have to do with that particular ASUS motherboard, as I had the same issue when upgrading another ASUS motherboard on little brother's PC (ASUS P5B-E Motherboard, P965 shipset).

For the P5B-E, the BIOS has a "Memory Remap" option, which according to some research, should be "disabled" for RAM amounts greater than 2GB in a 32-bit OS (but "enabled" for a 64-bit OS with greater than 2GB of RAM).

However, instead of showing the conventional 3.25GB, the ASUS board shows around 3.00GB (or 3008MB) when memory remap is disabled (and only 2GB when it is enabled). This is with Windows XP Pro 32-bit installed.

Another PC in the house has a Dell OEM (Foxconn) G33 based motherboard, and when that was upgraded to 4GB, it showed 3.25GB in Windows XP PRo 32-bit.

Its strange that both of your motherboard are ASUS, but one shows 3.25GB whereas the other shows 3.00GB.

This thread has more info which may possible help:

http://www.overclockers.com/forums/showthread.php?t=577233

 

[tcsenter]

Newer Intel chipsets don't need manual remap on/off setting.

 

[taltamir]

Newer Intel chipsets don't need manual remap on/off setting.

what are newer?
P55? P45? P35?

What does memory remap actually do and why is it needed?

 

[StrangerGuy]

what are newer?
P55? P45? P35?

What does memory remap actually do and why is it needed?

IINW, the classic 32-bit 4GB addressing has the devices that utilize memory space such as video cards "eating into" the 4GB addressing space, so even if you installed 4GB of RAM you will not get to use the full 4GB because the entire 4GB addressing space is shared between the main RAM and other devices. So if these devices uses 0.5GB of memory space, you only get 3.5GB of RAM left to use.

Since now with have CPUs that support more than 32-bit addressing what memory remap does is to map these devices way beyond the initial 4GB space so the system gets to utilize all the 4GB of RAM.

 

[taltamir]

IINW, the classic 32-bit 4GB addressing has the devices that utilize memory space such as video cards "eating into" the 4GB addressing space, so even if you installed 4GB of RAM you will not get to use the full 4GB because the entire 4GB addressing space is shared between the main RAM and other devices. So if these devices uses 0.5GB of memory space, you only get 3.5GB of RAM left to use.

Since now with have CPUs that support more than 32-bit addressing what memory remap does is to map these devices way beyond the initial 4GB space so the system gets to utilize all the 4GB of RAM.

so, just to make it clear.
You are saying that if your mobo does not have memory remap, and I use a 64bit OS and 4GB of ram, I will lose a portion of my usable ram (GPU ram + the other reserved ram).
And only mobos with memory remap allow a 64bit OS to not lose ram like a 32bit OS would?

 

[StrangerGuy]

so, just to make it clear.
You are saying that if your mobo does not have memory remap, and I use a 64bit OS and 4GB of ram, I will lose a portion of my usable ram (GPU ram + the other reserved ram).
And only mobos with memory remap allow a 64bit OS to not lose ram like a 32bit OS would?

I don't how much experience with this memory remap thing. The only board I fiddled with that is an old S939 GF6100 Gigabyte board which must be enabled for my 64-bit Win 7 to use the full 4GB DDR1. With my 965P and later boards there was no memory remap option in the BIOS anymore...Put in 4GB and it all 4GB will just simply work.