2011 MBA's - i5 1.6 GHz vs i5 1.7 GHz

[dmk1974]

As I still contemplate which 2011 MBA I want to keep (the 11" with i5 1.6/4GB/128 GB or the 13" i5 1.7/4GB/128 GB), I'm wondering why I see such a huge difference in benchmark scores for the processors? I mean, it's only a 0.1 GHz differnece, but the Geekbench scores are like 20% higher for the 1.7 for some reason?

And for further comparison, the MBP 2.3 i5 is then only 7% faster than the 1.7 (even though it's an additional 0.6 GHz faster processor). Am I just missing or not understanding something? Thanks!

 

[gloss]

It's more than just clock speed. Bus speed, RAM cache, etc all play into overall processor performance.

 

[KPOM]

The biggest difference is the Turbo Boost. The 1.6GHz processor boosts up to 2.0GHz with both cores running and 2.3GHz with one core running. The 1.7GHz processor boosts to 2.4GHz with both cores running and 2.7GHz with one core running. 2.4GHz is 20% faster than 2.0GHz, and that's the speed the processors are running at most of the time.

It's more than just clock speed. Bus speed, RAM cache, etc all play into overall processor performance.

All of those are the same between the two i5 models. The i7 model has 1MB extra cache, and boosts a little bit faster (2.6GHz in dual core and 2.9GHz in single core), but otherwise is the same, too.

 

[mountains]

As I still contemplate which 2011 MBA I want to keep (the 11" with i5 1.6/4GB/128 GB or the 13" i5 1.7/4GB/128 GB), I'm wondering why I see such a huge difference in benchmark scores for the processors? I mean, it's only a 0.1 GHz differnece, but the Geekbench scores are like 20% higher for the 1.7 for some reason?

And for further comparison, the MBP 2.3 i5 is then only 7% faster than the 1.7 (even though it's an additional 0.6 GHz faster processor). Am I just missing or not understanding something? Thanks!

Intel lies about its processors' speeds. Really, it does.

The 1.6 GHz i5 has a nominal speed of 1.6 GHz, but because of Intel's TurboBoost it's able to reach higher speeds as core temperature allows. It has a turbo multiplier of 0047, which means it can actually turbo up to 2.0 GHz (4 bins for 400 MHz turbo) with both cores active, or 2.3 GHz (7 bins for 700 MHz turbo) with one core active.

The 1.7 GHz, however, happens to be a beast. It has a turbo multiplier of 007A, which means it can turbo up to 2.4 GHz (7 bins) with two cores active, or 2.7 GHz (10 bins; A represents 10 in hexidecimal) with one core active. So it may not look much faster than the 1.6 GHz i5, but the 1.7 is actually a whole lot faster.

 

[KPOM]

Intel lies about its processors' speeds. Really, it does.

It lies in a good way, however. They could probably legally argue that the 1.6GHz chip is a 2.0GHz chip, and the 1.7GHz chip is a 2.4GHz chip. For whatever reason, they don't.

 

[dmk1974]

Thanks for the replies. So it's really the Turbo modes that differentiate the processors. Kinda screwy the way they rate them in listings, but I get it. Doesn't exactly make it easier in deciding between the 11" and 13" though. If the 11" was faster, it'd be a slam dunk for that one. I know I can get an i7 in 11", but don't really want to pay the extra.

Here's a comparison I found on the Intel site:
http://ark.intel.com/compare/54620,56858

 

[macbookpro45]

Don't pay the extra. The marginal advantage you gain is offset by the cost you have to pay for the i7 anyway

 

[Razzz]

if you have the 11inch go for i7.
for 13inch get the i5

 

[macbookpro45]

if you have the 11inch go for i7.
for 13inch get the i5

What is the premise of your argument for suggesting this?

 

[vitzr]

Unless you're doing some very resource intensive work it's simply not worth it.

Limited to only 4GB ram, you're not going to be able to take advantage of the full capabilities of that processor anyway.

And if you do need the power, then you should be looking at a MacBook Pro.

I use a new 15" MBP configured with 8GB & SSD, for my engineering and design work. For the rest, I use a new 13" MBA, that's a good combo.

 

[orfeas0]

if you have the 11inch go for i7.
for 13inch get the i5

I wouldn't suggest an i7 in the 13inch. It's gonna get too hot.

 

[dmk1974]

I wouldn't suggest an i7 in the 13inch. It's gonna get too hot.

Yeah, I think I've ruled out an i7 in either size. Just gotta figure if I want a bit more power (13" w/i5 1.6) or portability (11" w/i5 1.6).

 

[KPOM]

What is the premise of your argument for suggesting this?

The CPU performance difference between the 1.6GHz i5 and 1.8GHz i7 is about 20-25%. The difference between the 1.7GHz i5 and 1.8GHz i7 is about 8-10%.

 

[ZBoater]

I wouldn't suggest an i7 in the 13inch. It's gonna get too hot.

Ummmm, no, it will not. Or should I say it DOES not.

 

[QuaziModo]

Ummmm, no, it will not. Or should I say it DOES not.

I completely agree with this. My 11" Ultimate does not get hot at all, unless I really am hammering it. The initial problems which people were reporting I think had to do with some thermal transfer issue which has since been sorted.

I've got 6 desktops and apps on each of them right now and SMC says 48 degrees. It is barely warm on my lap right now.

The decisions on middle run MBA's seems like a hard one to me as I need a machine for 3 years. Though if you are more lucky than I then perhaps a cheaper model every 18 months could work for you?

 

[richpjr]

I wouldn't suggest an i7 in the 13inch. It's gonna get too hot.

Not my experience at all.