how to calculate increased cpu performance from increased core count?

[GunsMadeAmericaFree]

I'm considering upgrading my cpu. I'm currently using an AMD Athlon II x2 2.8 GigaHertz. I also recently purchased a Biostar TA880GU3+ motherboard, and I'll be installing that in the next few days. (from a ~3+ year old Asus board)

My main consideration is increasing the speed of video encoding using Nero Recode. I'm trying to figure out the gain for adding additional cores, but can't seem to find concrete statistics online. I understand, for example, that going to a 3 core cpu will not add 50% to my speed, nor will going to 4 cores double my current processor's results. I believe I read somewhere that there is a somewhat diminishing return. My current vague guess is that going from 2 cores to 3 cores would add about 40%, while going from 2 to 4 cores might increase my frames processed by about 70%. I realize that upping the processor speed would also further increase the results. I'm surprised that I don't see any 5 core processors for sale, since I also see 6 core ones. (a bit out of my price range - I'm going to spend $110 or less)

Can anyone point me to anything online that gives a better idea, for cpu intensive tasks like video encoding, of the exact gain from adding each additional core?

Thanks!

 

[Voo]

Depends mostly (ignoring some other factors) on amdahl's law and therefore on the specific software you're using and how well its code is parallelized. So without further information about which software not much we can say..

 

[Kevmanw430]

It depends on how much load there is on the two cores.. If you are using 100% of the CPU when doing encodin, then getting a quad core of the same speed, if all 4 cores are still maxed, should, theoretically double the speed at which you are processing.

 

[GunsMadeAmericaFree]

Depends mostly (ignoring some other factors) on amdahl's law and therefore on the specific software you're using and how well its code is parallelized. So without further information about which software not much we can say..

Software is Nero Recode 4.4.40.2 (latest update for Nero 9)

I don't need anything exact, just wondering (roughly) what increase I would get going from 2 cores to:

3 cores 3.4 GHz - $93
4 cores 3.2 GHz - $105

 

[notty22]

I would go for the Phenom II X4 955. If your considering the phenom 840. The added L3 cache is easily worth 20 dollars more. The phenom naming on the 840x4 confuses some.
The 955 is 112.00 at Fry's, Microcenter- 120.00 online if your in the usa.

 

[Blastman]

My current vague guess is that going from 2 cores to 3 cores would add about 40%, while going from 2 to 4 cores might increase my frames processed by about 70%. I realize that upping the processor speed would also further increase the results.

Many well threaded video encoding programs can come very close to doubling performance with the move from 2 to 4 cores. Sometimes it may depend if there are overhead tasks that are not well threaded.

Anandtech x264 .. First pass (fps) … second pass (fps)

Athlon II X2 255 (3.1) … 39.8 … … … … 9.2
Athlon II X4 645 (3.1) … 70.2 … … … … 18.2

The first pass doesn't double performance 76%, but the second does 98%.

In any case, 4 cores will bet better than 3 or 2 cores for any well threaded application, and video encoding does tend to be very well threaded these days. Definitely spend a few extra $ for the 4 core processor.