Some things to point out and the reasons behind the decisions (* this is
mainly pointing out the benefits and there is one or two counter points like
with power on one card while non-idle being slightly more efficient):
Here are some quotes from the review I'd like to point out:
"it took these higher-end Radeon HD graphics cards on AMD's open-source
driver in order to compete with Intel's open-source driver and their latest
integrated graphics."
"The Nouveau graphics cards could not be tested since with this driver and
Ubuntu 12.04's X.Org Server, Nexuiz does not run"
In addition one reason the 9500GT is better right now than the 9800GT:
"With the Nouveau re-clocking the card was unstable at the factory-rated
state, so it had to be tested at its boot frequencies of 399MHz for the core
and 399MHz for the video memory. As a result when running under Nouveau the
GeForce 9800GT performance is severely hampered" and "So the 9800GT in this
card represents the crippled child".
9500GT:
"The first NVIDIA graphics card being tested is the GeForce 9500GT. This G96
graphics processor from 2008 is well supported under the Nouveau driver. In
fact, recent testing has revealed that for some OpenGL workloads it offers
performance comparable to the binary driver."
When comparing ATI to Intel:
"it took these higher-end Radeon HD graphics cards on AMD's open-source
driver in order to compete with Intel's open-source driver"
The Intel graphics chipset was also the most efficient chipset using just 40
watts when idle in this review. In some instances "Ivy Bridge graphics being
more than twice as efficient" (than the low end Radeon HD 6450).
"The open-source Nouveau and Radeon drivers still lack good power management
support."
Conclusion:
"Overall the Intel Core i7 3770K "Ivy Bridge" HD 4000 graphics performance
was very competitive with its Mesa DRI driver compared to the tested AMD
Radeon and NVIDIA GeForce hardware on their open-source Gallium3D drivers."
"when it comes to those interested in open-source GPU drivers, Intel is
largely leading now with Ivy Bridge. "
and
"Besides very good performance and power efficiency compared to the discrete
Radeon and GeForce graphics cards on open-source drivers, the open-source
Intel Linux driver does offer VA-API video encode/decode acceleration"
