AGP vs. PCI?
Home | Reviews and Features | Special Reports | Forums |

Results 1 to 5 of 5

Thread: AGP vs. PCI?

Hybrid View

  1. #1
    Join Date
    Jun 1999
    Location
    pocatello
    Posts
    1

    AGP vs. PCI?

    What are the differences between PCI and AGP video cards. Which one is better?

  2. #2
    Join Date
    Mar 1999
    Posts
    42
    The AGP Bus runs at 66mhz (133 in 2X mode) unlike the PCI Bus which runs at 33MHz
    also the AGP bus has direct access to system memory to store textures, the PCI bus doesn't

    AGP is Better.

  3. #3
    Join Date
    May 1999
    Location
    Hull, East Yorkshire, UK
    Posts
    34
    Yep, that's the way I understand it too.
    Go AGP!

    ------------------
    Keep on Rockin' 'n' Overclockin' ;-)

  4. #4
    Join Date
    Oct 1998
    Location
    Calgary, Alberta CANADA
    Posts
    1,289
    Something to consider is that not all AGP cards really support the AGP bus specification, and are basically nothing more than PCI cards on a faster bus.

    The AGP port is always 66mhz (unless you run your bus at 75/83/112/124/ bus speeds). AGP 2x shows that a card can transfer information at 2x the normal AGP transfer speed because it can transfer data 2 times per clock cycle (which is the 2X), but the card does not actually run 133mhz. I dont remember what the number is exactly, but it works out to around 500mb/sec memory bandwidth between the video card and the system memory. The thing here is that the Video card has to support DME. DME is Direct Memory Execution, and refers to using the system memory directly for texturing.

    When looking at an AGP card, the box may say, AGP 2x with Sideband support, when the card actually does not utilize DME, so the AGP spec is pretty much useless here. The card is not capable of directly accessing the system memory for texture storage, but it does load the textures to the card faster on initial load up than a card that does not support AGP 2x and sidebands, but if the texture load increases past the memory available on the card, this type of card will slow down considerably compared to a card that allows DME of textures.

    Not many games right now utilize this feature, but more are coming allong that do, and they will get a boost in performance.

    ------------------
    Collin J
    HWC Administrator
    Moderator: Support and General discussion.

    Sometimes I wonder...

  5. #5
    Join Date
    May 1999
    Location
    Hull, East Yorkshire, UK
    Posts
    34
    Ah, I knew AGP was 66Mhz, and couldn't fully work out that 2x stuff. I'm learning fast all the time. Thanks.
    I still say Go AGP though.
    Keep on Rockin' 'n' Overclockin' ;-)

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •