Originally Posted by sotti
He's not contridicting himself.
System level Things:
-The any OS can adress up to the full 4GB of memory. Fullstop
-The any OS will use some of the 4GB of address space for DMA devices instead of main memory, so the addressable physical memory is usually between 3GB an 4GB unless you have huge video card memory (if you had a DMA free setup you could get very near 4GB)
OS level things:
-The applications that run on Win32 are limited to 2GB of memory usage for all applications your are running in total, leaving the rest to the OS.
-If you want you can flip a switch that will let the applications use up to 3GB of physical memory.
In 64 bit world each application gets a full 3GB memory sandbox. This is an important distinction between the two OS's. Some games (The witcher, Company of Heroes, Dawn of War II) with full graphics will hit the 2GB app limit in vista and drop you to desktop with a system out of memory error. The same apps on a 64bit OS with only 2GB of physical memory will not encoutner the same error, because they have more address space.
Everything you put in this post is what I've been saying all along, not what foxbat has been saying, he in fact has been saying the opposite of this, but flipping back and forth throughout the post. Again, you just confirmed exactly what I've been saying this whole time: Windows 32bit can address 4GB of memory - devices in the system will use up some of this (as you said, DMA addressing, video card memory, etc). At no point in time in this thread have I been speaking about processes themselves, just the OS in general. I know that processes are limited to 2GB of memory (or 3GB with the switch), this is something I don't care about and haven't been speaking of because it's almost
a moot point when talking about an HTPC.
Edit: Also FWIW I have 5 computers - Windows XP 32 with 4GB physical memory, Windows Vista 64 with 6GB of physical memory, Win7 32 with 2GB physical memory, Windows MCE with 1.5GB of memory, and Windows XP 32 with 2GB of memory.
At 2GB+, none of the systems with more memory actually had any sort of speed increase, except in the most wild of scenarios (at one point I was playing 5 copies of WoW on one system, which obviously used ~4+GB of memory, in which case the 6GB of memory was needed). For normal system operating, watching blu-rays, playing games that use <2GB of memory (ie: pretty much all of them), there really isn't much difference. The fastest PC in my house (minus the video card) is Win7 32bit with 2GB of memory - my HTPC - because the HDs are faster, the processor is faster, and Win7 is faster. My Vista 64bit system with 6GB of memory and a quad core processor with a much faster Videocard than my HTPC is actually a lot
slower overall. The CPU speed is slower and (and this is the real issue) the hard drives are much slower. The SATA HDs in my Vista PC can sustain around 35MB/s transfer, but the SATA drive in my Win7 HTPC sustain around 85MB/s transfer - huge difference and much more noticeable than adding system memory
Lesson here is, memory is not the be all end all, and in fact for most applications having more than 2-3GB is completely unnecessary, so don't harp too much on installing a 64 bit OS unless you absolutely 100% know for a fact you need a crapton of memory.