Why are dual core processors slower??

[Accipiter22]

Just curious about this fact...it seems like all the dual core processors I see are slower, as far as clock speed goes, than their single core counterparts, and even lower single core models.

 

[Gatt]

2 cores, twice the heat. Top end of the Dual core will be lower than top end of single core due to heat dissipation, top end of Quad will be lower than Dual for the same reason.

 

[coldpower27]

Originally posted by: Accipiter22
Just curious about this fact...it seems like all the dual core processors I see are slower, as far as clock speed goes, than their single core counterparts, and even lower single core models.

Twice the amount of cores doesn't come free, you sacrifice some single threaded performance for substantial gains in multithreaded levels.

 

[sxr7171]

What if you have a single core at 2.4GHz and a dual core at 2.4GHz? Are you saying that a single threaded process will take longer? Is it due to scheduling losses?

 

[coldpower27]

Originally posted by: sxr7171
What if you have a single core at 2.4GHz and a dual core at 2.4GHz? Are you saying that a single threaded process will take longer? Is it due to scheduling losses?

When you have a Single Core at 2.4GHZ like the 3800+ and the Dual Core at 2.4GHZ like the 4600+, you get a situation where performance is equal or better in Single threaded apps and up to double in multithreaded applications. Though there is quite the price difference between the 2 models and hence doesn't come free.

 

[PhatoseAlpha]

In addition to heat, there's a basic yield issue here. Even in single core processor, all manufactured with the same process, some chips will reach higher top speeds then others. See that all the time in varying overclocks.

Consider: Your process yields chips, of which about 50% of cores can hit a given speed. In single cores, that's 50% of your chips can be sold at that speed. With a dual core though, 50% will have the first core able to hit those speeds. Of which, only 50% will also be able to hit that speed with the second core. So, instead of 50% of your chips being able to be sold at a given speed, only 25% can.

If you get up into the higher, rarer to hit speeds - well, if you make it so only 5% can hit a speed, that gives you 5% of your single core processors that can be sold at a speed. Not much, but enough for limited distribution. With your dual cores, only 5% of that 5% will also have a second core that hits that speed. only a quarter of a percent of all your dual cores can be sold at that speed though. If the base is 1/2% of single cores, then only 2 in 100,000 of your dual core chips will hit that speed.


It's a linear increase in rarity versus a quadratic one.