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Radeon 4870X2 Question

Last response: in Graphics & Displays
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August 29, 2008 5:13:56 AM

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
Quote:
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.

More about : radeon 4870x2 question

August 29, 2008 5:37:40 AM

It has 2GB total, but "only" 1GB usable per card.
August 29, 2008 5:53:00 AM

Right, so then why would ATI even bother putting 2GB on the card in the first place?

Maybe I don't understand the reason for putting 2GB total and only 1GB usable on a card, but it sounds like ATI are just wasting 1GB for no reason.
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August 29, 2008 6:01:46 AM

When they tell you there are 2gig, it's just a marketing ploy. They should be MADE ( by law ) to say that the cards only have 1gig because that's all that's available.
August 29, 2008 6:11:36 AM

Yep, thats exaclty what I thought. Not to worry, everything I've read about the 4870X2 leads me to believe that its not suffering due to the "loss" of half its memory
August 29, 2008 6:14:30 AM

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.
August 29, 2008 6:14:52 AM

Swifty, 2 GB is available, you can access it for GPGPU and other apps, however currently the typical gaming mode is to have it mirror the information essentially giving you 1GB.

But yeah you work hard on that legislation.
Forget something important, gotta protect the gamers from their own stupidity. :lol: 
August 29, 2008 6:48:12 AM

what I was getting at is that the advertising is misleading the public................... hence the beginning of this thread............ this guys not alone.
August 29, 2008 6:54:32 AM

I've always been a strong believer in bit rate/clock speeds over raw memory ever since I got a 6600GT (128MB version that slammed the 256MB 6600).

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?
August 29, 2008 7:09:55 AM

ranky26 said:

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.
August 29, 2008 7:14:12 AM

swifty_morgan said:
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?

Quote:
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.
August 29, 2008 1:55:33 PM

It has 2GB total, but "only" 1GB usable per core
August 29, 2008 2:47:01 PM

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.
August 29, 2008 8:18:53 PM

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
!