Quad Core vs Dual Core Hyperthreaded Processor

Solution
In general, having 4 cores is better than having 2 cores with Hyper Threading. To get into the more specifics though it depends what CPUs you are comparing.

Duo core mobile Intel i5 vs. quad core mobile Intel i7 -
Assuming both have the same clockspeed, the Core i7 will perform just as well or better than the Core i5. In situations where only 1 or 2 cores are being used, they will perform equally. When 3 or 4 cores are being used the Core i7 will perform better

If the Core i5 has a higher clockspeed, then in this situation when only 1 or 2 cores are being used, it will perform better than the Core i7. However, when 3 or 4 cores are used the Core i7 will perform better. Of course, if there is a huge clockspeed difference like a...

I read that general applications run faster off of a dual core than a quad core. Just because they weren't designed for quad core. Is this true?
 


If the dual core has faster cores then yes, it will run better on programs that use only 1 core. If the cores of the dual core and quad core are of the same speed, then they would perform similarly (note that you cannot directly compare clock speed (GHz) of different processors of different companies/families to each other since there are many other variables that effect the actual speed of the processor other than just the clock speed).

With modern CPUs you will see little difference in just general applications.
 
Also keep in mind those 2 extra cores on the quad core will help big time for multitasking. They will handle background processes from the OS and other running programs and services while your single/dual threaded programs are using 1-2/4 cores keeping things running smoother.
 
In general, having 4 cores is better than having 2 cores with Hyper Threading. To get into the more specifics though it depends what CPUs you are comparing.

Duo core mobile Intel i5 vs. quad core mobile Intel i7 -
Assuming both have the same clockspeed, the Core i7 will perform just as well or better than the Core i5. In situations where only 1 or 2 cores are being used, they will perform equally. When 3 or 4 cores are being used the Core i7 will perform better

If the Core i5 has a higher clockspeed, then in this situation when only 1 or 2 cores are being used, it will perform better than the Core i7. However, when 3 or 4 cores are used the Core i7 will perform better. Of course, if there is a huge clockspeed difference like a Core i5 @ 4GHz and a Core i7 @ 1GHz, then I will guarantee you that the Core i5 would beat the Core i7 without even trying. However, those CPUs do not exist.

Duo core mobile Intel i5 vs. quad core mobile AMD APU -
Intel CPUs simply provides better performance than AMD APUs when comparing individual cores. Each core in a Core i5 will outperform each core in an AMD APU by probably 30%. This is not to say you will get 30% better frame rates in games with the Core i5. I speaking of pure CPU processing power. Assuming the same clockspeed, you will get better performance with the Core i5 in programs that only uses at most 2 cores. This is a generalization since performance differences actually depends on the program. Taking the 30% performance difference an AMD APU clocked at 2.6GHz would be equal to a Core i5 clocked at 2.0GHz.

In applications that can make use of up to 4 cores, then the tables will likely turn assuming both Intel CPU and AMD APU have the same clockspeed. Again, it depends on the program, but I think the AMD APU would provide better performance than the Intel Core i5.
 
Solution
What if I'm opening Firefox browser playing Youtube video, then run a virus scan software, then play a DVD on Windows Media Player, then run a stock market trading software with real-time stock quotes coming into my stock charts, etc. How do I check which core or which thread is doing what? Is it possible that all these tasks are running on only 1 core because of the way the software is written?
 

First of all, all applications run on threads, which then handle it to the core.
Threads can be translated to process(more or less).
a dual core with hyperthreading have 4 threads, and a quad core without hyperthreading have 4 threads.
A programmer cannot decide which threads will be used to his process, he can decide how many and how important they are.
Windows will assign each process to a thread. A thread can only handle 1 process at a time.
As I dont know which 2 processors your are looking at, I cannot say which one will handle all those task best.



 

I'm using a Intel Pentium Dual-Core E5200, I believe with no hyperthreading. Is there a simple way to tell which program is using which core? I'm thinking of upgrading to i3-4130 Haswell (2 cores/4 threads) or i5-3350P Ivy Bridge (4 cores/4 threads) but not sure how to even see which core is doing which job.
 

I havent myself used a program like that, but I do believe it should exist.
I cannot see the reason someone havent made that program. Try do some googling and you should be able to find it, hopefully.