4gb of video memory
- Thread starter Tempered81
- Start date
Even if the graphics drivers only use the memory footprint of one card, won't the memory from all 4 cards map over the system memory when the system boots? Would it be impossible to boot a 32-bit OS on this system?
True. jaredpace is right of course, it is 4GB of physical memory, but yes, CrossFire/SLi only use the GDDR of the first card.
Ummm, yes its 12MB of cache...? So the Q6600 has only 4MB of cache effectively?
Oh I think I see what your saying, a 2 socket system. Not 2 cores on 1 die. Even then, I dont know how the dual socket system acts, so it may act like a single socket system w/ 6MB, or it may perform/behave like a single socket system w/ 12MB... haven't had the opportunity to read up on it.
Keysplayr
Elite Member
- Jan 16, 2003
- 21,211
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That is "sort" of true in that all the memory on all four cards have the same data in it. So essentially, it is only 1GB of "data" being processed at any given time. The upside? If rendering SFR, the each card is responsible for 1/4 of the frame load. Leads to insane AA. Also if AFR is used, then each card renders a frame in sequence.
Card 0: renders frame 1
Card 1: renders frame 2
Card 2: renders frame 3
Card 3: renders frame 4
Card 0: renders frame 5
Card 1: renders frame 6
Card 2: renders frame 7
Card 3: renders frame 8
Care 0: renders frame 9
Card 1: renders frame 10
etc etc.
The CPUs/cores have to keep their cache in sync or rather bad things would happen. Graphics RAM is just another type of cache.
Yeah.....and they're wrong... 2900XT's have two power connectors on the *top* of the card.
Those cards shown have *one* connector, that is at the back of the card.
Not necessarily. A 1 GB video card does not consume 1 GB address space.
See Peter's posts here:
http://forums.anandtech.com/me...rthread=y&STARTPAGE=22
In theory, if a Quad-Crossfire system were loaded up with enough other peripherals, then yes, there might not be address space enough for the OS to load.
To put it plainly, four 1GB cards in SLI or Crossfire still only equals 1GB worth of frame buffer. This is because the CPU sends the vertex data to the primary GPU which then copies the data to the secondary GPU. So in the case of quad SLI or Crossfire, you now have four 1GB video cards that all contain the same 1GB of data.
Once the data has been completely rendered, the compositing chip then sends the frames to the monitor at the correct time and in the proper order. Since you would now have four GPUs all crunching away on the data instead of one, the number of completed frames per second increases dramatically. This is how SLI or Crossfire gets its impressive power.
Once the data has been completely rendered, the compositing chip then sends the frames to the monitor at the correct time and in the proper order. Since you would now have four GPUs all crunching away on the data instead of one, the number of completed frames per second increases dramatically. This is how SLI or Crossfire gets its impressive power.
I don't think you read what I wrote (and linked to). If the cards individually use only 256 MB address space, that's only 4 x 256 MB = 1 GB drain on address space vs. your 512 MB drain on address space. So it would be 1.8 GB of RAM (out of 4) in a 32-bit environment, or worst case 0.3 GB of RAM. But we do not know how much address space a 1 GB card consumes.
graphics ram is not a cache. there isnt a copy of whats in the graphics ram anywhere else.
also the 2 cores on a q6600 do not have to have the same stuff in both of them.
it just has to have whatever thread that core is working on's stuff on it.
if they both happen to be working on the same data then yes whenever there is a write on one thread it would have to write through the cache to memory and then update the cache on both cpus if both were workin gon the same data that is getting written into.
that doesnt mean the caches cant have multiple threads, or if they arent working on the same thing it doesnt have to be the same data in both caches.
I don't know about you, but I don't consider SLI or Crossfire to offer 'impressive' power/gains.
As to the CPU/Cache statements. The only person who can really address that is the original poster (swtethan). I was simply trying to guess what he ment... I was not stating how (i think) cache on a cpu works. Oh I see, you were 'talking' to aka1nas?
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