CPU Speed vs L2 Cache Size?

[DakotaDuce]

Hi All..

I have a interesting dilemma. Purchased a "PcChips M863G" motherboard.. along with a stick of "Kingston KVR333X64C25/256 DDR 2700 Dimm CL2.5" memory. The bios allows me to independently set both the CPU and Dram frequency to either 100-133-166. I have two AMD 2600+ Athlon XP CPU's that I can use. That's the dilemma!

CPU #1:
AXDA2600DKV4D
Level 2 cache............ 512
Family.Model.Step...... 6.10.0

CPU #2:
AXDA2600DKV3D
Level 2 cache............ 256
Family.Model.Step...... 6.8.1

A test of both CPU's (using AMD's CPU Id and CPU Info programs at all three frequencies) showed different readings when it came to the CPU speed, even though all other factors remain the same.

At 100:
CPU #1..... 1.150 Mhz.
CPU #2..... 1.250 Mhz.

At 133:
CPU #1..... 1.533 Mhz.
CPU #2..... 1.667 Mhz.

At 166:
CPU #1..... 2.086 Mhz.
CPU #2..... 1.916 Mhz.

Most of my computer use is that of "web page design", along with surfing the internet and e-mails. I don't do any gaming, heavy graphics or music files. The rest of my system consists of the following..

25" High 8 Bay Super Tower
Maxtor 120gig 7200rpm HD (14 Partitions)
Maxtor 40gig 5400rpm HD ( 5 Partitions)
Sony DRU-500A Dual RW DVD/CD
CyberDrive CW099D 52x CD-R/RW Burner
16 Assorted Circulation Fans
550w Twin Fan Power Supply

I use the existing "on board" audio, video, USB, Lan, etc. and don't plan on installing any slot cards. This being the case.. "is there any advantage using one CPU over the other.. or do I just throw both up in the air and which ever one lands on the ground I use? Is it better to have the "2086 Mhz speed" or the "512 Level 2 Cache"?

Thanks..
Dakota Duce

 

[Triton101]

If web design, and web surfing is all you do then you probably will not notice the difference. The later revision of the cpu AXDA2600DKV4D (with the 512 cache) is approx 100Mhz slower, but it does have more cache. Only cpu bench mark utilities will show you if on your system one cpu is faster than the other. My take on it is, you wont see much of a difference.

 

[ceh4702]

The speed of a processor is more than Mhz. Today a processor may have multiple pipelines. These pipelines all execute code at once. It is by adding all the pipelines up that that a true calculation for theoretical speed of a processor is determined. It is a lot more complicated than that, so I will just say the true sense of speed of a processor is how fast it can perform a given task that some other processor can perform, all things being equal.

Even a processor may be fast the data has to get to the processor. Instructions and data is pulled off the hard drive through memory and to the Cache of the processor. The throughput speed and the bus speed of the FSB are key factors to how fast the computer will actually go. One way a computer goes faster is to keep more of these instructions and data in the cache memory and the registers that are on the CPU. By doing this it takes less time to retreive them. So The speed of the hard drive, the speed of the memory Throughput and the size and speed of the Cache Memory systems and the registers all are key factors for speed.

If the data and the instructions are all run at once on each pipeline that means things are run out of order. Processors also have devices which predict what will need to be done next. They use algorithms to predict the future. How well this works and how long the pipelines are part of the processor speed. If it does not work well then all the data and the instructions and the results sitting around waiting to be used has to be discarded and then new data and instructions have to be loaded. This takes time and the longer the pipeline, the longer it takes.

I hope this helps a bit.

If you do not like my post feel free to point out your opinion or my errors.

 

[dakota81]

That's the beauty of AMD's performance ratings, over the majority of software, they will perform roughly equal. I'd go with the lower MHz & higher cache version, though, as I know it's a newer revision and puts out less heat.

However, more to your actual choice making, when tossing the cpu's, I'd actually take the one that doesn't fall to the ground. =)

 

[paparazi]

What you are talking about here is:

A Thoroughbred B XP2.6+ CPU with 256kb of L2 Cache running at 2086mhz AND
The newer Barton core XP2.6+ running at approx 1920mhz

I've tried them both on my Nforce2 GA-7NNXP and there is nothing in it (I have the Barton core XP2.6+ fitted ATM)
I did read a very interesting review on the two which did put the older Thoroughbred B very very slightly ahead of the Barton but this was "miniscule"
One thing everyone agrees though is the Barton core not only runs cooler but is a much better overclocker.
Bottom line is the Barton can run rock solid stable moderately overclocked (with adequate cooling)
thus easily outperforming it's older variant.
Other than than they are basically equal.
Martin

Replying helps further our knowledge, without comment leaves us wondering.

 

[SirNuke]

I would personall always go with the more l2 chache. Mhz is very, very overrated. The P4s have high mhz and fsbs but suffer from poor l1 + l2 chache (speed and size), along with having a very, very long pipeline. Shorter pinelines are MUCH better.

Quick explaination: CPU often 'guess' at out come of somewhat slower math calucalations. The guess is sent to the pipeline. When the real calc is finished the CPU checks the guess. If it is wrong, it has to erase the pipeline and start over.

I belive (DO NOT QUOTE ME ON THIS) that the newer XPs have one stage shorter pipelines.

SirNuke

 

[cdogg]

SirNuke,
Both types of pipelines have their advantages and disadvantages. When intelligent caching schemes are required (such as in typical Office or 3D apps), shorter pipelines have the edge. In other types of demands when the pipeline is fed at a constant rate ("plug and chug" such as in audio or video encoding), the P4 architecture comes out ahead.

But yes, the point is that the architecture as a whole plays an equally important role to overall performance - it's not just about the MHz rating.


~cdogg
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