I recently ordered a Sapphire 4870X2 after reading this review, plus a few others.
One thing that has me slightly confused however is at the bottom of page 2 where it states
For all intents and purposes, the X2 behaves like a card equipped with 1 GB of available memory, just like the GeForce GTX 280.
I thought the card had 2GB of video memory, so I'm wondering why I've seen multiple reviews say the card only has 1GB of available memory. Have ATI just put "2GB" to make the 4870X2 sound better or is all 2GB going to be useable.
I may be mistaken, but I believe the problem (if you want to call it that) is that while both cards have 1 GB each (totaling 2 GB), the contents of the memory must be duplicated for each card to be able to render it's share. That is, the way the load is balanced in SLI and Crossfire (an expert could confirm this, perhaps) requires that each card have everything loaded into memory. So while there are 2GB of physical memory, you can only load a total of 1 GB of data (but you load it twice, spread out of 2 GB of physical memory). As I understand it, the only way to avoid this situation is to change the way the cards share the load.
So, to surmise the situation, the fact is that these cards do have the advertised amount of memory. However, when people say things like "you need X ram to play this game or to play this game at a certain resolution", you will need twice that amount of memory (total) in a dual-card setup.
If ATI said that this card had 1GB of memory, people would assume that it had 512MB of usable memory.
Thanks for responses guys, I'm think I understand what is going on now. Am I right in thinking that one 4870X2 has 2GB, of which data is loaded into memory twice, similar to a raid-1 setup?
Yeah it's a similar idea, it that there's no increase in memory size nor in bandwidth, the difference of course being that it's not done for redundancy on a single processor, it's done for 2 separate processors.
what I was getting at is that the advertising is misleading the public...................
Because multi-gpu setups are so new and no one can research them?
hence the beginning of this thread............ this guys not alone.
Just because alot of people think one way doesn't make that correct, acceptable, nor the responsibility of others.
There is 2GB on the card, I haven't seen much that says ATi or nV are trying to fool people with their X2 / GX2 cards, and of the two configurations, 2GB doesn't offer much above 1GB, whereas the 1GB on the GX2 and HD4850X2 would be limited compared to a full 1GB of available buffer space.
Wow a slam from the Ape albeit deserved. If you want to see deceptive marketing look no further than the iPhone 3G. ATI is not doing anything deceptive and I'm proud 4870x2 owner though my first one was defective.
I think what sm may be confused about is when a low end card comes out with 1 gig of memory on it, thus it really is a decpetion, as those low end cards cant ever use that amount of ram, as they arent fast enough, nor "wide" enough