Good, good.. Should have dropped to just about the right price in time for the inevitable GTA upgrade requirement...
AMD has launched its two-GPU Radeon HD 4870 X2 graphic card, as expected, with a host of suppliers offering boards based on the design. AMD claimed it's the "world's fastest" graphics card. The first in our in-tray: Sapphire's HD 4870 X2. Both GPUs pack in 800 unified shaders in cores clocked at 750MHz. Each connects to 1GB …
Well actually It was 3DFX that did it before nvidia (and before nvidia bought them) but actually as far back as the ATi (now AMD) Rage card they did a dual GPU card - pretty much when 3DFX did one... so if you want to stick you head up Nvidia's arse in this pissing contest I'd get better information.
I'm sure this card is stupidly fast and in 2-3 years it'll affect normal people's graphic cards but for now, fast, expensive (though cheaper than Nvidia's best offering by quite a bit) and probably noisy but makes nice pictures. Wow ;)
In order for the computer to be able to read the graphics memory, it must be MAPPED into an address range. Now, in the 32-bit world, there are only 4 billion possible addresses you can use, but both the system RAM and the graphics RAM are getting so big they're competing for limited addressing space. Two CrossFired 4870X2's require the mapping of 4GB of memory. As it turns out, 32-bit addressing only has 4GB available. If you're going to be using one of these things (and definitely if you plan to CrossFire), you must use a 64-bit OS, whose address space isn't expected to be completely occupied anytime soon.
He's talking about the necessity to reserve address space for devices in 32bit Windows. Therefore removing the ability to address X amount of system memory.
Stick 4gig in a 32bit windows box then add a 512mb graphics card and watch the available system memory drop to 3.5gig for an example.
Wade, you might like to review how computers work yourself.
The 'memory' (simplistic view) of peripherals, like hard drive controller, graphics card, sound card, map their memory and IO addresses into main memory. On a 32 bit OS, the maximum addressable memory (in total) is 4 GB. If you have two of these cards, they each have 2 GB of memory on board that must be mapped into main memory.
4GB - ( 2 GB + 2 GB ) = 0, so I very much doubt two of these in crossfire will even work on a 32 bit OS - I imagine the second card will fail to be setup by the BIOS.
In fact, given that you need ~60-70 MB of addressable memory for other peripherals, put this card in a Vista 32 bit box with 2 GB of RAM, and you will end up having unaaddressable RAM.
Hopefully, they will say it is not Vista 32 compatible....
Thank you AMD!
Allow me to explain. The 4870HD is a great card, but I have a 3840x1024 desktop, so I need gobs of RAM on the card. My motherboard only supports SLI, so my current twin GeForce 7900GTXs are fine and dandy, but Crossfire for the 4870HD is a non-starter. This card gives me the power I want with the memory I need, at a bloody brilliant price. (Consider that my 7900GTXs were £200 *each*)
Nice one AMD! I'll bang one of those in my system as soon as I've sorted out this whole "buying a house" thing.
Well, strictly speaking only the memory mapped interface of the card must use address space, if the memory on the card wasn't directly mapped (via some kind of load operation, or if the display memory and z-buffer memory were unmapped) then it wouldn't necessarily occupy the full 2GB.
In short it doesn't have to be mapped, but almost certainly is.
well, i never knew about the 4850X2..
judging by these prices, i'd say that the 4850X2 could be a real winner..
imo, the single card solution is an 8800GT (at £85 is a joke considering what it can do), or a 9800GTX or a 4870.
if you MUST go multiple, as what seems to be currently the widely held view, 2 x 4850's in SLI is the way to go.
to that end, obviously a 4850X2 would give punters a single card solution.
btw, someone told me that the 4870X2 needs 410w of power. wtf.
stuff and nonsense: http://www.eupeople.net/forum
It really bugs me that you guys insult other people despite being completely incorrect.
So, just to shame I give you this;
"For example, if you have a video card that has 256 MB of onboard memory, that memory must be mapped within the first 4 GB of address space. If 4 GB of system memory is already installed, part of that address space must be reserved by the graphics memory mapping. Graphics memory mapping overwrites a part of the system memory. These conditions reduce the total amount of system memory that is available to the operating system."
Don't just take my word for it.
Time to speak to you careers officer, IT is not the place for you guys. Try politics, they get paid for talking shit.
I've got a 512MB 7650 GT in an XP system with 512MB system RAM
why does this run quite well if the video RAM is using all the address space of the same amount of system RAM .. eh ?
a bit confused by the comments .. but perhaps it's just that I'm not enough of a g33k that I should have this site as my homepage !
Paris, because you'd forgive her confusion on such matters
Because the limit only kicks in at 4gb using a 32-bit operating system. Explained another way:
512MB system ram + 512MB video ram = 1gb total ram. Under the 4gb limit, so perfectly acceptable.
4gb system ram + 2gb video ram = 6gb total ram. You'll see 2gb system ram and 2gb video ram. 2gb system ram will sit there doing nothing.
2gb system ram + 4gb video ram = 6gb total ram. You won't have any system ram to play with, which is a Bad Thing (tm).
Where we've produced this 4gb ram limitation comes from 2^32 which is 4294967296 bytes or 4194304 kbytes or 4096mb or 4gb.
Hope that clears things up for you.
As was previously explained, a 32-bit system addresses 4Gb of ram. The issue with the cards, if all of the onboard card ram is mapped into the main memory address space, is that two of them contain enough ram to use *all* of the addressable space. Your system (graphics + system) uses a total of 1Gb, well within the limit, so your graphics card and motherboard memory can both be mapped into the 4Gb limit address space.
A 64 bit OS can *potentially* address much more memory (up to a maximum of 2^64 bytes), but practical hardware configurations will likely address much less.
Just a thought: your system might run a little faster if you have at least 1Gb of system ram. 512Mb would have it paging like a bad thing under many scenarios. For example, running Unreal Tournament 3 under XP with this much ram means that the game is largely unusable.
It's not using RAM, it's using address space.
If you have filled the address space with RAM then the graphics cards _memory_mapped_ space will overlap and you either lose RAM or you lose graphics card.
In your case you have space for both so everyone is happy and gay.
BTW Doesn't the kernel immediately claim 1GB of address space in XP?
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