Question: 32bit OS and 4GB GPU RAM - What happens?

[sleepyhead]

OK, so here we are with various people on 32bit and 64 bit OS's.

Lets say someone has 32bit XP (or Vista) and has slapped in two 4870X2s which have 2GB each of onboard video memory. Lets also say you have 2GB of RAM on your machine.

As far as I can understand, a 32bit OS will only have maximum number of address (is that the right term?) of 2^32 which is around 4GB.

What happens?

P.S. This is nothing about me or a pc build, this is a thought I had whilst at work

[mmh]

dunno, but i got 4gb ram in a windows machine with a 512mb graphics chip and i only get just over 3gb use of the 4gb ram inside


gutted, as i didnt know the pagefile wouldnt take it when i ordered the ram

[chuckskull]

It will go horribly wrong, I can guarantee that. If it boots it'll probably be with 1.something RAM and one card usable.

[dangel]

As far as I can understand, a 32bit OS will only have maximum number of address (is that the right term?) of 2^32 which is around 4GB.

Yup total addressing available is 4gb - this has to be split between all devices and so the PC tries to reduce RAM to keep the PC usable. With 4gb of video RAM god only knows how it tries to cope - you'll either get severely reduced functionality or machine death.

Don't do it

[dangel]

dunno, but i got 4gb ram in a windows machine with a 512mb graphics chip and i only get just over 3gb use of the 4gb ram inside


gutted, as i didnt know the pagefile wouldnt take it when i ordered the ram

Pagefile? Pagefiles are used as 'fake memory' so that you can load more things into memory than you physically have they don't change the 32bit limit. Get yourself a copy of Vista x64 and then you can have it all

Also of note: 32bit OS' can't give a single application more than 2gb of memory (known as the process limit) either.

We really need a sticky on 32bit stuff, it comes up so much at the moment.

[Agent]

slapped in two 4870X2s which have 2GB each of onboard video memory. Lets also say you have 2GB of RAM on your machine...

What happens?

You get a Higgs Boson and put Fraz out of work.

Don't do it.

[Stoo]

You get a slap around the chops for having far too much disposable income

[GoNz0]

and complete the melting of the ice caps

[badass]

Pagefile? Pagefiles are used as 'fake memory' so that you can load more things into memory than you physically have they don't change the 32bit limit. Get yourself a copy of Vista x64 and then you can have it all

Also of note: 32bit OS' can't give a single application more than 2gb of memory (known as the process limit) either.

We really need a sticky on 32bit stuff, it comes up so much at the moment.

4GB per process. Windows by default can only allow 2GB as the other 2 GB is reserves as kernel address space. Using the 3GB switch in Windows server OS's changes the address space to allow 1 GB for kernel address space and 3GB for the process.
I suspect other OS's can in theory offer a gnats foreskin shy of 4GB should you desire, however it may be completely useless like that.

[TAKTAK]

in a nut shell

32bit = 4GB addressable space
64bit = 16TB addressable space

and if you had 2 4870x2's i highly doubt forking out £7 for x64 media from msoft is going to be that much of a problem

and if you manage to hit the limit on x64 you've done something wrong... (or it is 2050...)

[dangel]

4GB per process. Windows by default can only allow 2GB as the other 2 GB is reserves as kernel address space.

For all intentions the limit is 2GB per process - write a standard windows app and allocate blocks of 1024bytes and the system will stop handing you memory at 2GB (providing it doesn't halt the app allocation whilst it's increasing your pagefile to cope!).

[sleepyhead]

....

Don't do it

.....

Don't do it.

You get a slap around the chops for having far too much disposable income

I quote myself...

P.S. This is nothing about me or a pc build, this is a thought I had whilst at work

It literally was a thought I had after reading reviews of the 4870X2 in crossfire (versus Triple SLi GTX 280).

If I had the cash to do that I wouldn't be running a wonky E6750 on a flappy 650i chipset.

However it would be a rather interesting experiment for Hexus So c'mon lets do a machine review on what happens if you use a 32bit OS with 4GB of video RAM Machine death? Higgs Boson discovery? Tardis?

[directhex]

BeOS had a 1gb address limit, and just crashed if it was exceeded

[badass]

For all intentions the limit is 2GB per process - write a standard windows app and allocate blocks of 1024bytes and the system will stop handing you memory at 2GB (providing it doesn't halt the app allocation whilst it's increasing your pagefile to cope!).

I was quoting you mentioning the limit for a 32 bit OS is 2 GB per process.
For the average person running Windows, the limit is 2 GB, but that certianly isn't the limit for any 32 bit OS

[dangel]

I was quoting you mentioning the limit for a 32 bit OS is 2 GB per process.
For the average person running Windows, the limit is 2 GB, but that certianly isn't the limit for any 32 bit OS

Sorry I was obviously misled by you talking about windows in your post then..
Well that, and the OP is about Windows!

[sleepyhead]

I think it is something that needs to be highlighted. You could have someone who is running a 32bit OS (XP Home for example) who has a P35 motherboard and had a £800 bonus from work and thinks "ahh I'll get the 4870X2 GPU and double it!". Needless to say, bad things would happen.

When I first built PCs I knew nothing. Seriously.

Anyhow, we know NOT to do it but would love to see what would happen (and maybe get one of the 4870X2s for free )