Multiple GPU sockets and their implications with the OS

I learned something new last week.  I didn’t realize all 1024MB video cards aren’t created equally.  Apparently some of them have multiple GPU sockets and that has some interesting implications when using them for gaming and what the operating system sees for general purpose applications.

This all started a month or two ago when we were creating some configurations for video editing workstations.  I asked Chris Henley what he wanted and one of the things he suggested was a 1024MB video card.  Since we were building out the quote for a Dell XPS 420 and that was one of the options on the public ordering site, I added a 1024MB video card to the quote request.  We also added some other goodies to the quote and basically configured a nicely decked out machine.

The Dell XPS 420’s we ordered and received included the Intel Core 2 Quad Q9300, Dell 27” flat panel LCD, ATI Radeon 3870X2 1024MB GDDR3 video card, Blu-ray, fat hard drive, etc.  In short, a really nice video editing workstation.  The main purpose of the machine is to slice through video edits like a hot knife through butter.  The Dell XPS 420’s we received accomplish that as expected and we don’t have to worry about turning a laptop into a block of molten lava.

However, upon close inspection it appeared we didn’t receive the 1024MB card we received.  Here’s one of the screenshots from Windows Vista Ultimate x64:


Huh?  Where’s the other 512MB? I thought we actually received the wrong video card.  Seems plausible. There were only two clues in the UI of the OS or installed applications that tip you off on what is really going on.  In Device Manager, there are two video cards displayed.  What?  How is that possible?

The second clue is in the ATI Catalyst Control Center (CCC).  By the way, you have to get the updated drivers from the website for this card to work correctly with Windows Vista x64.  The drivers at the Dell site would not install.  When you look at the card in CCC, you’ll see a “Primary Adaptor” and a “Linked Adaptor”.

So what is really going on?

The answer is clearly shown in the picture at the top of the blog post.  If you look closely you’ll see that the card has two GPU sockets and chips.  It is effectively two cards on the same PCB.  Each GPU has 512MB of dedicated memory.  So technically it’s the correct card and it has 1024MB of memory, but how much do you think is being used by Windows Vista?  Unfortunately only 512MB unless you are running a game that understands the ATI API and will use both GPUs and their memory at the same time.

You wouldn’t know any of this unless you are a gamer I guess.  There is no mention of it on the Dell buying site and I certainly didn’t take the time to fully research the video card before we bought the configuration that arrived.  Since we aren’t using the machines for gaming (at least I am not), we are trying to determine what to do.  I’m inclined to return the card for a credit and look for a more suitable card for our needs.  I was thinking the Sapphire card at would be a candidate.  Anyone have an opinion on the build quality of Sapphire cards?  I’ve been using NVIDIA chipset's and BFG Tech video cards for years and have had very good luck with them.

Any other suggestions?  Have a 1024MB card with a single GPU that works well with Windows Vista x64 and has a reasonable price?  Let me know.

Oh, one other thing.  I forgot to mention in the picture of the card at top you’ll see a bit of engineering I really like.  Notice Dell has added a black piece of plastic to the card that extends it.  This allows the end of the card to slide into a slot in the XPS 420 and it really stabilizes the card very effectively.  A simple bit of engineering that produces a great result.  That should be a standard in the industry.

Comments (5)

  1. Gkeramidas says:

    i’ve used sapphire in the past and they were ok. right now i have an msi 9600gt w/512 and 1 24" lcd connected to it and an msi 9800gt w/1G and 2 lcds, 24" and 28". seems to work fine even though the only 2 drivers sets are a whql candidate and a beta.

    but, so far no issues with vista x64 business.

  2. tinman says:

    Whoa. I want YOUR job O.O

    Why the hate for Nvidia? 😉

    A simple $200 8800GT 512MB could slice through editing, and lay some waste to Crysis too. If you’re looking for something with a little more muscle, maybe a 9800GTX would suit your needs. It’s definitely a powerful card, gaming and off, though the 8800GT is no small contender. I really can’t say much about ATI because I’ve stayed a safe distance away…

    I hear if you stay too close for too long you start liking Macs. Be ye warned.

  3. Simon says:

    Why on earth would you need a graphics card with 1 gig memory for video editing?!?

    The only applications that can use this much memory are games or CAD-stuff using 3D textures or LOTS (! LOTS !) 2D textures.

  4. Brian says:

    I agree with Simon,

    You only need more than 256MB on a graphics card for games – not even CAD programs use much gfx memory (usually).

  5. Keith Combs says:

    I personally don’t need that much memory because I am not using the machine for anything that intensive.  In fact, I am returning the multi GPU video card.

Skip to main content