Processor Clock Speed

Jackobyte

I don't know a whole lot about the innards of computers and I just have a question about a processor in a computer I'm looking at.

I understand that the higher the clock speed, the faster the processor works. What I don't understand is that the i7 740QM only has a clock speed of 1.73gHz, much lower than the i5 or the i3, yet it is more expensive? Why is this?





Does the fact that the i7 is quadcore make up for this? Do you multiply the clock speed by the number of cores to get the actual processing power or what? So would it be:
i7: 1.73x4=6.92gHz
i5: 2.53x2=5.06gHz

A quick response would be appreciated because the item has to be ordered in the next 24 hours for Christmas Delivery.

Thanks,
Jackobyte.

P.S., to those who told me to custom build when I last posted, I did a u-turn and decided to go with a laptop instead. Thanks for your help anyway.

Voodu Child

When all 4 cores are being used, they are clocked at 1.7GHz. It cant go any higher because higher clockspeeds need more voltage per core, which would result in too much heat altogether.

But if all 4 cores arent being effectively used, then what it does is shut down one core, resulting in less heat output. So it can use that saved heat to overclock the other 3 cores.

Thats what turbo boost is.

And it will do the same, all the way down to 1 core if necessary. When it is running 2 cores I think each core is clocked at 2.5GHz, which is compareable to the i5-540M.

Jackobyte

Voodu Child wrote: »

When all 4 cores are being used, they are clocked at 1.7GHz. It cant go any higher because higher clockspeeds need more voltage per core, which would result in too much heat altogether.

But if all 4 cores arent being effectively used, then what it does is shut down one core, resulting in less heat output. So it can use that saved heat to overclock the other 3 cores.

Thats what turbo boost is.

And it will do the same, all the way down to 1 core if necessary. When it is running 2 cores I think each core is clocked at 2.5GHz, which is compareable to the i5-540M.

Thank you. All I wanted to know was that it was definitely faster than an i5.

Voodu Child

Jackobyte wrote: »

Thank you. All I wanted to know was that it was definitely faster than an i5.

When apps you are running are effectively multi-threaded (good at using many cores) then it is faster.

When they are not, then it is about the same. Maybe a small bit slower when only using a single core. But you're talking 2.9GHz vs 3GHz, tiny difference.

Cant really put it any simpler than that. Some apps are highly multi-threaded and some arent.

Jackobyte

Voodu Child wrote: »

When apps you are running are effectively multi-threaded (good at using many cores) then it is faster.

When they are not, then it is about the same. Maybe a small bit slower when only using a single core. But you're talking 2.9GHz vs 3GHz, tiny difference.

Cant really put it any simpler than that. Some apps are highly multi-threaded and some arent.

Are many apps multithreaded?

Overheal

Many. But not all. And thats when i7 technologies come into play. All that hyperthreading and turboboost are technologies on the die that attempt to split the processing requirements of a single thread program across several cores. In some examples like gaming, some multicore processors will shut down or idle some of their cores to direct more power into fewer cores resulting in higher clock speeds and such.

Ultimately however it doesnt get calculated on a 2x1.7 basis. It's like horses and carts: 4 horses can pull the cart up to 25mph, regardless of the weight of the cart, but not up to 100mph.
Except that in some case an i7 absorbs 2 horses to make 4 horses into 2 stallions, etc

Also the cache data is a very important stat and determines how many processes the stack can handle.. but basically the bigger the better. It's a very very very fast but small area of memory where the processor decides what it needs to do next.

the nm process is kind of but not as important, it basically determines how much heat and energy are required to run things, and also determines how many transistors can be squeezed onto a single die. The i7 will consume a little more power and run a little warmer but its a fair tradeoff for the increases in performance provided. However noting these are M/Mobile chips, you want to factor that into your decision, as power consumption and a little extra heat might not be a big deal in a desktop but in a laptop they're rather key.

Jackobyte

I went with the i7 740QM anyway.

RoyalMarine

Jackobyte wrote: »

I went with the i7 740QM anyway.

should have bought a horse.

Jackobyte

RoyalMarineComm wrote: »

should have bought a horse.

What?

RoyalMarine

read overheal's post above