32-bit RAM Limit

[TheUnk]

So I just added an HD4870X2 to my PC. These babies have 2GB.. My PC has 2x2GB sticks. All that totals 6GB. It was my understanding that the 2GB on the video card would take from the system and therefore only leave me with 2GB system ram since 4GB is the 32-bit cap.

But several programs report that I have 3.2Gb of system ram.

Whats going on here?

I need to get Vista 64bit =p



Moved to Operating Systems.

Video Mod BFG10K.

 

[Raider1284]

found this link pretty useful. http://www.laptopvideo2go.com/...ex.php?showtopic=17165

 

[bsobel]

Your video card has 2gig on board, but that doesnt mean all of it is mapped into the 32bit address space. Thats why your seeing 3.2 free.

 

[corkyg]

Bsobel is correct - "seeing" and "using" are two different things.

 

[Scotteq]

Originally posted by: TheUnk
So I just added an HD4870X2 to my PC. These babies have 2GB.. My PC has 2x2GB sticks. All that totals 6GB. It was my understanding that the 2GB on the video card would take from the system and therefore only leave me with 2GB system ram since 4GB is the 32-bit cap.

But several programs report that I have 3.2Gb of system ram.

Whats going on here?

I need to get Vista 64bit =p



Moved to Operating Systems.

Video Mod BFG10K.

I have a 4870X2 myself - It has 1GB worth of Memory Mapped I/O, not two. The other GB of memory on the card is used to replicate data for the two processors - i.e. Processor 1 has 512MB of #2's data, and 2 has 512 of #1's.

That is why you see more memory than you think you should.

 

[Peter]

Graphics chips typically map a 256-MByte window into system space, not a flat view of their entire RAM. This is done exactly because else 32-bit systems would be left with too little space left for system RAM.

Your X2 card maps twice that (probably). You can see for yourself in Device Manager if you can compute hex.