As most readers probably know, nVidia and ATI are the
one-ton gorillas of the videocard market. These two perennial powerhouses have
been jousting back and forth for top spot in the graphics market for years now.
ATI currently holds the overall performance crown, but nVidia has a stranglehold
on the lucrative mid-range market with its 6600GT GPU as of the writing of this guide.
Since there's a 95% chance that any recent computer uses a video card from
one of these two companies, this article deals primarily with overclocking those
products. While the primary purpose and effect of overclocking ATI or
nVidia videocards is the same, the software and even the procedures used can
differ, so each company's cards are covered in a separate section.
The most recent video cards from either company tend to be highly
overclockable, though historically nVidia has held an advantage in this
regard. Some previous-generation cards from ATI have a form of
overclocking 'lock' implemented on them, causing the core and memory clock
speeds to return to stock as soon as a 3D application or game is started.
More on this later in the article.
Updating Videocard Drivers
The first thing to do before overclocking a videocard is
to acquire the most recent driver set for it. NVidia's ForceWare and ATIs Catalyst driver sets are universal, meaning
they cover all recent videocards made by their respective companies. All that
needs to be done is to visit the website of the card's manufacturer and download
the latest version of the drivers, then install them. Note that at
the time of this guide, the latest version of the RivaTuner utility used for
overclocking in this article did not fully function with the latest version of
the ATI Catalyst driver suite (5.5), though it still worked for overclocking
purposes. Readers may want to stick with the Catalyst 5.4 drivers for full
functionality until an update is released.
Benchmarking and Overclocking
This article assumes that readers are already familiar with (or at least are
aware of the existence of) the common 3D performance benchmarking programs like
To get the best out of an ATI or nVidia videocard in terms of overclocking, a
consistently repeatable 3D benchmark like FutureMark's 3DMark 2001SE or 3DMark05
is needed to test the new settings each time core or memory speeds change.
Since most modern videocards run at slower speeds when rendering a 2D image
such as the Windows desktop, the fact that a card can render the desktop
correctly when overclocked is not a real test of its stability. To truly
test an overclocked card's stability, a full-screen 3D benchmark needs to be run
completely and without error.
Download 3DMark 2001SE or 3Dmark 2005. For an nVidia 5xxx or 6xxx
series card, or a Radeon 9xxx or Xxxx series card, use 3DMark05; otherwise, use
Install 3DMark and run the (non-overclocked) system through a round of the
benchmark with everything at its default setting. Record the final
score. This is the baseline for comparing the video card's performance
before and after overclocking.