What is the difference between dual-core and quad-core processor in terms of performance?
A multi-core chip can execute multiple instructions at the same time.
Dual cores have two cores, and quad cores have four. All the cores are on the same chip though. So, they share the same memory, and data path to the motherboard.
So, a quad core chip may be able to execute the instructions four times faster, but that doesn’t mean it can receive instructions from ram four times faster.
Also, the faster a CPU is, the hotter it gets. Just because the CPU is a quad core doesn't mean it was set to run at the same gigahertz.
Consider a manufacturer that wants to sell a 4 gigahertz chip, but the core keeps melting. One could sell a Quad core chip with each core set to 1 or 2 gigahertz and get increased performance, but still be running each core much slower. Therefore the chip no longer melts.
Software has to be rewritten to take full advantage of multi-core processors. The operating system might provide a small automatic increase in speed, but you won’t see a 4X increase in performance simply by switching to a quad core.
Even if the software is rewritten it might not be 2X, or 4X faster because now the program may have additional instructions added for the sake of figuring out which core is going to access each part of the program.
I'm a big fan of dual-core systems. I think there's a clear and substantial benefit for all computer users when there are two CPUs waiting to service requests, instead of just one. If nothing else,
it lets you gracefully terminate an application that has gone haywire, consuming all available CPU time. It's like having a backup CPU in reserve, waiting to jump in and assist as necessary. But for most software, you hit a point of diminishing returns very rapidly after two cores.
In Quad-Core Desktops and Diminishing Returns,
I questioned how effectively today's software can really use even four CPU cores, much less the inevitable eight and sixteen CPU cores we'll see a few years from now.
To get a sense of what kind of performance improvement we can expect going from 2 to 4 CPU cores, let's focus on the Core 2 Duo E6600 and Core 2 Quad Q6600 processors. These 2.4 GHz CPUs are identical in every respect, except for the number of cores they bring to the table.
In a recent review, Scott Wasson at the always-thorough Tech Report presented a slew of benchmarks that included both of these processors. Here's a quick visual summary of how much you can expect performance to improve when upgrading from 2 to 4 CPU cores
