1. Welcome to TechPowerUp Forums, Guest! Please check out our forum guidelines for info related to our community.

overclocking AGP bus speed - good or bad?

Discussion in 'Overclocking & Cooling' started by denoxis, Sep 21, 2005.

  1. denoxis New Member

    Joined:
    Sep 21, 2005
    Messages:
    4 (0.00/day)
    Thanks Received:
    0
    Hi,

    I have this MSI Neo socket 754 mobo with Athlon 64 3200, 1GB RAM and 6800LE AGP video card.

    In the BIOS, there are 2 overclocking options. One is the CPU bus speed, and other one is AGP bus speed, which were 200MHZ and 66MHZ by default. I increased them to 210 MHZ and 70MHZ about 2 months ago. Last week when the game demo FEAR failed (blue screen of death with nv4_disp.dll went in to infinite loop) I read it could be some timing issue betwen the graphics adapter and mobo.

    I did two things:

    1) Installed the lates mobo drivers
    2) Pulled the bus speeds back to 200MHZ and 66MHZ.

    Not only game worked, Aquamark score increased by couple thousand points. :confused:

    So after that I started wondering wheter OC'ing AGP speed is something I shouldn't do or I should do considering other parameters (for example core speed, or other factors)

    What do you think? Any technical explanations are welcome :)
     
  2. djbbenn

    Joined:
    Apr 11, 2005
    Messages:
    2,736 (0.72/day)
    Thanks Received:
    44
    Location:
    Canada
    Don't overclock it, not worth it. You can a bit, but it will cause instability. When you overclock, its like a standard to lock AGP/PCI bus.

    -Dan
     
  3. gerrynicol New Member

    Joined:
    Feb 8, 2005
    Messages:
    758 (0.20/day)
    Thanks Received:
    18
    Location:
    Scotland, Falkirk
    Whilst o/cing DON'T raise PCI/AGP speeds these buses are really bad at o/cing, you should have an option to "lock" these at 66Mhz and 33Mhz, choose this option.
    I think you should also try a search for overclocking on the forums/google before you try again. Just keep settings at default until you read up, understand what each setting does then start , gradually raising settings. also you may want to purchase a better CPU cooler.

    lol just beet me to it Dan :(
     
  4. M. Mellough New Member

    Joined:
    Oct 3, 2005
    Messages:
    97 (0.03/day)
    Thanks Received:
    0
    Location:
    Maine, USA
    Not locking the AGP bus to 66Mhz will seriously limit your CPU overclocking potential because increasing CPU FSB speed also automatically raises AGP bus speed in order to maintain clock ratio and the AGP bus will reach its stability limit way before the CPU clock does. The result will be an unstable machine even with a modest CPU overclock leading many overclockers to be mislead into believing they have reached their CPU's performance limit.

    The reason why this is not widely known yet is because until recently most CPU overclocks were achieved through multiplier manipulation which has no effect on the AGP bus. Now that Athlons (Bartons and 64's alike) have locked multipliers most overclocking is done by raising FSB speed, which has a chain reaction effect on both RAM speed and AGP bus speed. While it is important to maintain ratio between CPU and RAM for synch reasons the AGP bus is best left alone, i.e. locked to its default clock speed. In order to achieve good results AGP overclocks should be done separately from CPU and memory speed tweaking.

    Sorry for the long post but I see this issue posted on many hardware forums and I figured I may as well share what I have learned about it. Locking the AGP bus has allowed me to achieve much faster CPU overclocks than I used to. Using this method on an XP 3000+ (Barton) whose default clock speed is 166Mhz, and Corsair PC3200 RAM I was able to raise it to 211Mhz without experiencing any stability issues whilst without locking the AGP bus I was only able to take it to 186Mhz before it started crashing on me, using the same RAM sticks. Clearly, the bottleneck was the AGP bus.
     

Currently Active Users Viewing This Thread: 1 (0 members and 1 guest)

Share This Page