Overview

Many people ask, "How many cores do I need for my system?" I am doing X. here is my assessment of the situation.

app threads usage

• dreamweaver CS5 - 15 threads active
• photoshop CS5 - 22 threads active
• compiler - 1 active thread
• antivirus - mcafee takes 142 threads when sitting idle, 90 active when scanning (that will chew up cores like crazy, no wonder it's so slow...)
• OS - XP Pro takes 1000 threads, most of them idle
• compression - as many active threads as you assign
• video encoding - as many active threads/cores as you have, depending on program
• audio encoding - as many active threads as you assign or have, depending on program
• office or other single-threaded apps - 1 active thread
• multithreaded/multicore apps - all the cores you've got
• browser - firefox 5.0 takes 40 or more idle threads, probably 1 active (I have 40 tabs)
• build CD/DVD ISOs - 1 active thread
• VLC - 17 active threads
• quicktime - 17 active threads
• windows media player - 21 active threads

adobe premiere takes all you've got during certain operations like rendering. I think photoshop does also, like during content aware-whatever and 3d stuff. You can figure the other adobe products to take an average of 15-22 threads each, and chew up lots of memory. I have a 32-bit system with 3GiB of RAM, 4GiB of VM, and I can only run 2 adobe apps at the same time MAYBE with Bridge in the background (so make that a total of MAYBE 3).

Your usage?

the idle threads you can essentially ignore - for a time - they might become active at some point. but active? ahh there's the rub. most people only use 1 app at a time. some people like developers and people who use authoring software have some long, slow processes, so someone might do video encoding while they are doing batch compiling or some other long slow job in the background. maybe several. I have been known to build several DVD ISOs in series-parallel while doing other stuff like browsing with 40+ tabs.

are you a multitasker? or a single-tasker? is your intent to make as much use of your computing power as possible? or are you extremely focused on one thing?

I have a single core with 2 threads. (pentium 4 HT).

I say, grab as many cores as you can afford. it always helps. it already sounds like 30 cores is too few for me, just for my antivirus...

The reality is, more and more software is becoming multicore-aware or multithreaded.

size up your situation and make an accounting of your apps you intend to use, then figure out how many cores you are going to need, then buy a machine. Before I made this assessment, I had long thought that anything under 30 cores is under-powered. this only proves it.

cpu comparison

take this into consideration: an i7-995x Extreme cpu has 6 cores and 12 threads total (2 threads/core). the AMD has only 1 thread/core. The AMD is mid-list, the slower processor by about 1/2. The i5's are at the bottom of the list. the i7 extreme processor is faster than all but 1 top-of-the-line Xeon processor. however, it's limited to only 24GB of memory, which makes me sad. Photoshop chews up many GB of RAM for breakfast when doing panos. one guy was considering expanding beyond 64GB on his workstation.

passmark cpu benchmark tests for fastest CPUs

workstation?

If you have $24000 ($24K) lying around and need raw compute power, dual i7 cpu's or xeon cpu's, or you need up to 192GB of RAM, then you need a workstation. If you are doing rendering, you need a RenderBOXX. CAD. Authoring software like Adobe products. There are other reasons for using a workstation, such as scientific research and maybe even mathematics.

xeon cpu's can handle 192GB of RAM each (and it's typically shared). i7 cpu's can handle 24GB of RAM. but the i7 cpu's like on the 3DBOXX are faster and can be OC'd if you use liquid cooling.