Last week we looked at the performance
of ATI’s Radeon X1800XT videocard when at stock settings
and compared it to numerous other videocard configurations
including the GeForce 7800GTX. On the whole the XT was ahead
of the GTX in performance when using DirectX based titles.
When using OpenGL the performance leader was the GTX. What
we also looked at in that article was the new GPU design
that ATI were using and made comment on how it differs from
Over the past week we’ve seen some
comments from people interested in just how good the G70
would be compared to the R520 if both had the same
number of pipelines and clockspeeds. So off
we went to see if it was possible to get the required configuration
up and running.
By default a 7800GTX is 24pipes clocked at 430mhz with 8
vertex units and memory clocked at 1200mhz. With the help
of rivatuner we were able to ensure the card had 8 pipelines
disabled while leaving the 8 vertex units intact.
Next up we used Powerstrip to set the 7800
to a clock which was as close as possible to the R520. The
clocks we settled on which provided no artifacting etc were
Following the above steps we confirmed
that performance had changed in the expected direction from
a 24/8 or 20/7 G70 based card.
Next up was the R520 and getting it as
close as possible to the above clocks. Using an internal
ATI tool we were able to down clock the card to 455/1000
(due to the limitations of the clocking utility there was
a 5mhz difference between cards however the performance
difference caused by this should be negligible). As the
R520 already uses 16 “pipelines” and 8 vertex
units no further alterations were needed.