Why Are AMD CPU's slow on DVD Shrink?

[wulf109]

AMD CPU's seem to run very slow with DVD Shrink. For example my Athlon 64-3200+ takes 24 minutes to trancode what my Celeron D 3.2Ghz does in 21 minutes. Shouldn't they at least be equal.
I thought AMD's PR rating was it's speed in Ghz. A 3200+ AMD should perform like an Intel at 3.2Ghz?. I've got an Athlon X2-3800+ that takes 14 minutes to trancsode compared to my D805 at 3.3Ghz taking 9.5 minutes. All AMD chips seem slow compared to Intel on DVD Shrink.
I'm using the same 3 hour episode disk for all tests.

[jagabo]

AMD's PR ratings are only a rough guide. Different apps will behave differently.

[nonoitall]

Netburst (Pentium 4 and most Celerons) is a very different architecture from K8 (Athlon 64, Sempron 64). The rating is just meant to give you a general idea of how an AMD processor performs compared to an Intel equivalent. Actual performance for "equal" processors varies from application to application with AMD shinning in some areas and Intel in others. AMD is usually better with floating point calculations, while Intel is better with integer operations, which would explain why AMD tends to do better with gaming, while Intel does better with multimedia encoding.

IMO, dual-core CPUs have completely thrown AMD's rating system out of whack. An X2 3800+ (dual-core) runs at 2.0GHz, so for single-threaded tasks, it should perform about the same as a 3200+, which also runs at 2.0GHz but has one only core. The 3200+ is roughly equivalent to a 3.2GHz Pentium 4, which basically means that an X2 3800+ (which is like two 3200+'s working together) is roughly equivalent to a 3.2GHz Pentium D (which is like two 3.2GHz Pentium 4's working together). Confusing enough?

To get an idea of just how an AMD CPU compares to an Intel one, I'd multiply the AMD processor's clock speed by 1.6. This can be used to get a very rough comparison between:
1. Athlon 64 and Pentium 4
2. Sempron 64 and Celeron/Celeron D
3. Athlon 64 X2 and Pentium D/Pentium EE

Bare in mind that the same logic can't be applied to Intel's Core 2 processors, since they use a completely different architecture.

[budz]

This CPU chart maybe helpful to you.

http://www23.tomshardware.com/cpu.html

[RabidDog]

DVD Shrink may just be very sensitive to the actual raw clock speed of the Proc its on eg amd 3800 runs at about real clock of 2.2ghz. Its just one program among many. Many progs tend to get optimized for Intel Cpus as they might use an intel optimizer when compiled? Amd cpus do more per clock cycle, sometimes however this is not enough to overcome their deficit in raw clock speed. Be interesting to compare two chips with the same clock speeds, with dvdshrink.

[jagabo]

Amd cpus do more per clock cycle, sometimes however this is not enough to overcome their deficit in raw clock speed.

That's only true when comparing Athlon family to Pentium 4 family processors. Intel's Core processors have slightly greater IPC than A64. In any case, it's all very dependent on what programs you are running.

[ybeard]

Same amount of memory and exactly the same programs running in the background? Are the DVD drives you are reading from exactly the same and/or rated the same speedwise?