i5 vs i7 - What are they?

Oskar1921

macrumors newbie
Original poster
Mar 2, 2010
14
0
I've tried to find this via a search but just can't pin it down. I'm new here and constantly see references to i5 & i7 iMacs. What is the difference and how can you tell. Thanks.
 

TMRaven

macrumors 68020
Nov 5, 2009
2,099
1
i5 and i7 are quad core processors of intel's newest nehalem architecture, which is a newer and improved cpu architecture compared to the core2duos.

Nehalem provides on average 20% more cpu prowess per clock speed compared to older architecture, and also has other features such as hyperthreading and turboboosting-- which is essentially the cpu overclocking itself if not all cores are being used.

i5 is a quad core and supports turbo boost, but no hyperthreading.
i7 is a quad core and supports both turbo boost and hyperthreading, it also has a slightly higher clock than i5.

A lot of programs don't support hyperthreading right now, but for stuff like video encoding, you will really see a difference.
 

Hellhammer

Moderator emeritus
Dec 10, 2008
22,076
580
Finland
They are both Intel's CPUs. They are just code names for different products. The main difference is that i5 has Hyper-Threading disabled while i7 has it enabled. i7 also runs at higher clock speeds.
 

Dr.Pants

macrumors 65816
Jan 8, 2009
1,181
2
I've tried to find this via a search but just can't pin it down. I'm new here and constantly see references to i5 & i7 iMacs. What is the difference and how can you tell. Thanks.
The difference between the i5 and i7 iMacs and the older C2D iMacs is that the i5/i7 models use quad core processors from a much newer architecture then C2D (dual-core). You can tell by going into System Profiler and looking at the processor.

The difference between i5 and an i7 processor is that the i7 model is a slightly higher clock speed and hyperthreads as compared to the i5.

EDIT - next time Hellhammer I won't take a couple extra minutes to post ;)
 

Hellhammer

Moderator emeritus
Dec 10, 2008
22,076
580
Finland
Is the i3 the new Celeron?
Yeah, you can think like it is:

i3 = Celeron
i5 = Pentium
i7 = Core 2 Duo

It may not be the "right" way of thinking it because Core 2 Duo and Core ix are the same Core family so... I would think that:

i3 = E7xxx
i5 = E8xxx, Q8xxx
i7 = E8xxx, Q9xxx

I doubt there's a "right" way of seeing this as Intel naming system is so confusing
 

mystikjoe

macrumors regular
Jan 29, 2010
217
1
I've tried to find this via a search but just can't pin it down. I'm new here and constantly see references to i5 & i7 iMacs. What is the difference and how can you tell. Thanks.
the difference is bragging rights to say you have the i7!

i've yet to see a single instance that i can tell the difference in speed between the 2. i had the i5 for 3 weeks and now the i7 for a week. either one is a winner!
 

Hellhammer

Moderator emeritus
Dec 10, 2008
22,076
580
Finland
I was surprised to find all the mobile i5 chips are dual core. I didn't know the iMac uses the desktop version.

Cheers,
iMacs didn't before the last update. All 32nm CPUs are dual-core for now but Gulftown is coming in few weeks and it's six-core and Lynnfield might go 32nm later on this year. Maybe Intel had problems making a 32nm quad core CPU so they decided to kept all consumer CPUs dual core and gave Hyper-Threading a try as well or something like that.
 

JackLeBoul

macrumors newbie
Mar 5, 2010
26
28
Zurich - Switzerland
Bootleneck

Coming from a Mac Pro and bought an iMac (i5+8GB ram) for the wife and kids one I did notice a few observations.

- Great machine for its price
- Handy to have everything "on the table" without cables
- Fast CPUs
- Relatively "cheap" ram upgrades

But the bottleneck with this machine is the HD. Yes it is 1TB 7'000 rpm etc etc,
but it is the slowest thing on the machine. Using Aperture 3 or iMovie, one does wait for the HD quite often to react. Unfortunately, the new iMacs have a new thermal heat sensor plugged in to the HD, which makes it very difficult to uppgrade to SSD or "non" compatible HD's.

http://blog.macsales.com/2751-proprietary-cable-can-put-the-brakes-on-upgrading-late-09-imacs

Again, the choise of CPU will be in fact secondary to the overall speed of the machine IMHO.

Jack
 

Badger^2

macrumors 68000
Oct 29, 2009
1,962
2
Sacramento
But the bottleneck with this machine is the HD. Yes it is 1TB 7'000 rpm etc etc, but it is the slowest thing on the machine. Using Aperture 3 or iMovie, one does wait for the HD quite often to react. Unfortunately, the new iMacs have a new thermal heat sensor plugged in to the HD, which makes it very difficult to uppgrade to SSD or "non" compatible HD's.
Jack
So then put a SSD in the optical bay?

http://www.mcetech.com/optibay/

or http://forums.macrumors.com/showpost.php?p=8942262&postcount=250

I rarely use my optical drive in my iMac. Got a perfectly good (and much faster) external.
 

Raima

macrumors 6502
Jan 21, 2010
397
7
Not all intel i5s are quad core. The i5 processor apple has selected to use in the iMac is a quad core.
 

Hellhammer

Moderator emeritus
Dec 10, 2008
22,076
580
Finland
Is Hyper threading useful for new games? Or is not supported there either?
I think not. There aren't many games that supports quad-core so I doubt they support HT yet. New games supports quad-core though and I think in future they support HT as well. Game industry is always little behind other software industry
 

mystikjoe

macrumors regular
Jan 29, 2010
217
1
Badger^2,

On MCE site they mention MacBook Pro as compatible systems.
I did not see the new iMac's. I guess you tried it out and it worked?

Jack
it works fine although you can find other ones for half that price that do the same thing!
 

glhiii

macrumors regular
Nov 4, 2006
213
35
Sata input missing

I can't believe Apple has such powerful machines and doesn't let you upgrade the hard disk -- at least they could have a SATA input.
 

niuniu

macrumors 68020
I think not. There aren't many games that supports quad-core so I doubt they support HT yet. New games supports quad-core though and I think in future they support HT as well. Game industry is always little behind other software industry
I checked this out after you replied, you're right, and there's even a lot of articles on the net about games performing Worse with HT turned on (due to some sort of latency).

Think I won't lose sleep if the new MBPs come with i5 only