Blender speed

Hi everybody.

I have a question on the speed of Blender on different CPUs : I just built a new PC with a Pentium 4 3.4GHz and it seems that it is not a lot faster than my previous PC built with an Athlon XP 2000+.

So I made a test, with the same Blender version, the same scene, the same renderer settings, and here are the results :
Athlon XP 2000+, CPU used at 100%, 1 minute 21 seconds for rendering the scene.
Intel P4 3.4 GHz, CPUs used at an average of 50%, 1 minute 16 seconds.

During the test, I realized that the two (virtual) CPUs of the P4 were running at only 50% on average :o .

Does somebody know why Blender does not use 100% of the CPUs on Intel P4?
Is this something that can be corrected with a Blender built dedicated for Intel P4 ?

Thanks in advance for your answers.

There is a CVS build here which is optimised for Intel P4 and AMD processors which support the SSE2 instruction set. Why not try it out. The author is looking for benchmark tests.

Thanks rwv01. I tested the built. Speed is better, now the rendering time is down to 55 secondes, but my CPUs are still used only at 50 % on average during the rendering calculations…

Anybody having a Dual Core P4 having the same problem ?


did you try pressing the threads button in the render buttons?

Same problem here: I have an Intel Pentium 4 3.4 Ghz (lke yours, I think). Even with multithread, CPU usage in the Task Manager stays on 50% average.

When you say Athlon XP 2000+, what is the actual gHz of that thing?

AMD seems to “mask” their true CPU speed by giving their chips fancy high-tech numbers as the name of the chip. Or they say “up to XXXgHz” on their packagges.

AMD processors are typically a little faster than their Intel counterparts… which is why they started renaming them. Customers thought the bigger the number, the faster the processor, which when your comparing processors/products from the same company/brand makes sense… but it is not a good way to compare the processors from intel and amd. I’ve been a big AMD fan lately. Cheaper and faster… unfortunately they also run a bit warmer than intels… :slight_smile:

So just because one has a higher reported processor speed doesn’t mean its gonna be faster.

z3r0 d, THANKS !!!

When I click on the Thread button, this is what I get, with the same scene and same rendering options :

  • official 2.37 A Built : 55 secondes
  • Spécial 2.40 Alpha 1 built for P4 : 44 secondes

So if I take the official version, I get 55 secondes instead of 81 secondes with a P4 instead of Athlon XP200+
If I take the special built, I get 44 secondes for the P4 instead of 81 secondes for the Athlon XP 200+.

With the special built, that’s almost a 2X gain. Incredible !

Thanks a lot !

the 2000+ is 1.7Ghz [1.69 acutally] … its what I have at home

Best results I have are with this build :
This is twice faster than any other build I tried including the one pointed in this thread.
I use a laptop with pentiumM 1.6GHz and 512Mo of ram.