4890 Crossfire -- Big Improvement going to 64-BIT OS?

[Razrback16]

Current setup is in my sig. Running Vista 32-BIT. I am curious as to how much performance improvement I would see in games if I went to Windows 7 64 Bit (my primary thinking on this is due to 64-bit being able to address all my RAM -- system & video)?

Thank you.

[SoulsCollective]

Yes, definitely, but any improvements won't be related to Crossfire.

As you seem to be aware, 2^32 = 4GB total addressable space, out of which you need to map every hardware device in your system, everything with any cache from CPU to HDDs to VGA. In a common system, after all hardware mapping for basic devices is taken care of, you usually wind up with about 3.7GB left, out of which then comes VGA (in your case, 2*1GB = 2GB), and then finally the remainder is used to map your system DRAM - which means for you that out of the 4GB of physical RAM installed in your system, only about 1.7GB is actually addressable.

As you can see, as VGA RAM is addressed first, you're not losing any VGA performance, which is what the thread title implies - but you are losing out significantly in gaming due to the extremely low (by today's standards) amount of system memory you can actually access. You may, however, see in Control Panel that Vista is recognising more RAM - this would be due to PAE.

PAE stands for Physical Address Extension, and effectively raises the total amount of RAM "seeable" by essentially constructing a secondary mapping table that your system can look to - but any one process can still only access what it could before PAE - so in this case, while 4GB of system RAM may be recognised by Vista, any one app can only access 1.7GB of that 4GB.

In short, yes, going 64-bit will give you a significant improvement and yes, it's worth the trouble of reinstalling.

[W1zzard]

any 32 bit app can only address up to 2 GB of memory, even on a 64-bit os

[EniGmA1987]

^^^^
Good to know

[Razrback16]

Yes, definitely, but any improvements won't be related to Crossfire.

As you seem to be aware, 2^32 = 4GB total addressable space, out of which you need to map every hardware device in your system, everything with any cache from CPU to HDDs to VGA. In a common system, after all hardware mapping for basic devices is taken care of, you usually wind up with about 3.7GB left, out of which then comes VGA (in your case, 2*1GB = 2GB), and then finally the remainder is used to map your system DRAM - which means for you that out of the 4GB of physical RAM installed in your system, only about 1.7GB is actually addressable.

As you can see, as VGA RAM is addressed first, you're not losing any VGA performance, which is what the thread title implies - but you are losing out significantly in gaming due to the extremely low (by today's standards) amount of system memory you can actually access. You may, however, see in Control Panel that Vista is recognising more RAM - this would be due to PAE.

PAE stands for Physical Address Extension, and effectively raises the total amount of RAM "seeable" by essentially constructing a secondary mapping table that your system can look to - but any one process can still only access what it could before PAE - so in this case, while 4GB of system RAM may be recognised by Vista, any one app can only access 1.7GB of that 4GB.

In short, yes, going 64-bit will give you a significant improvement and yes, it's worth the trouble of reinstalling.

I really appreciate the feedback. Just to clarify -- you're positive my OS is using all of the RAM on my two video cards? That was my main concern. Systems performs great in 2D apps, and great in gaming as well, I was primarily concerned that due to my 32-BIT OS that all of my VRAM wasn't getting addressed.

[flopper]

windows 7 is a good OS, especially 64bit.
I would get it if I still used Vista.