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Which imac i5 or i7 Quad Core

post #1 of 12
Thread Starter 
Hi All,

This is my first post on the forum I have been browsing for quite some time.
I was waiting for the new Imac to come out before switching from PC to Mac.

I am so glad that Apple have put Quad Core processors in to their new imacs, I know have a dilema, which one do I go for?

Should I go for the i5 or i7?

My main use will be the normal internet, email, word processing etc and HD Video editing and eventually music production using logic.

Thanks in advance for your help.
post #2 of 12
I was able to save $550 going with the i5, so that pretty much sealed the deal for me. For most people I expect the difference is not as large, but I was able to get a discount from buying a stock configuration.

Performance benefits of the i7 are mostly centered on memory bus, including RAM and PCI-express. The iMac's RAM is consistent across both models, so no benefit there, and the PCI-express bus isn't utilized heavily, either.

Based on what I've read, the i7 in the iMac is at best 10% faster than the i5 is. This takes into account the higher clock speed. Realistically, expect 5% performance gains, since memory is often the bottleneck, and they both have the same memory.

The i7 seems to me like it is there for the guys who must have the very best, and not for anyone else.
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post #3 of 12
What about going from the dual core to i5? How much of a performance gain should I expect? I mean, right now, the dual core 2.66 is already good enough for me as i dont do any heavy video/graphic editing. But buying the new imac makes me wanna think a couple of years ahead, is the i5 necessary just to maintain a workable performance 3, 4 years down the line?
post #4 of 12
Most people may not see any difference between the two (C2D and i5/7) right now, but history will show us that 2-3 years down the road, the i5/7 will be a MUCH better machine to have on your desk.

As Apple continues to refine OSX and other apps (as well as 3rd parties) they will begin to take advantage of the newer chips (efficient use of multi-cores and hyperthreading)... If you want your machine to be able to run the latest versions of advanced software and take advantage of all it's "stuff", then 2 years from now, you'll wish you'd bought the i5 or even i7.

(Similar to the way some Intel Macs (Core Solo?) can't take advantage of all the features of SL.)

If you plan on replacing it 2 years from now anyway, then it might be worth saving a couple hundred for now and running with a C2D.
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post #5 of 12
Quote:
Originally Posted by KingOfSomewhereHot View Post

If you plan on replacing it 2 years from now anyway, then it might be worth saving a couple hundred for now and running with a C2D.

The resale for the Quad cores, I expect, will make up for the higher cost.
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post #6 of 12
I'll say this, either will be heads and shoulders above the C2Ds in the rest of the line, but if you can swing the extra $200...
post #7 of 12
Thread Starter 
Quote:
Originally Posted by Splinemodel View Post

I was able to save $550 going with the i5, so that pretty much sealed the deal for me. For most people I expect the difference is not as large, but I was able to get a discount from buying a stock configuration.

Performance benefits of the i7 are mostly centered on memory bus, including RAM and PCI-express. The iMac's RAM is consistent across both models, so no benefit there, and the PCI-express bus isn't utilized heavily, either.

Based on what I've read, the i7 in the iMac is at best 10% faster than the i5 is. This takes into account the higher clock speed. Realistically, expect 5% performance gains, since memory is often the bottleneck, and they both have the same memory.

The i7 seems to me like it is there for the guys who must have the very best, and not for anyone else.

Thank You Splinemodel,

I was going to get the i7 Processor but if I'm going to get a very small increase in performance I may as well save my self some cash and go for the i5

Thanks again
post #8 of 12
The Core i7 supports hyperthreading (aka HT); the i5 does not. HT lets your system run extra threads per processor; in essence, a Core i7 system has 4 actual cores and 4 'virtual' cores. Right now, very few programs can take advantage of these 4 'virtual' cores, but in the future (2-3-5 years), HT use will easily become common (for heavy-duty apps, mostly).
post #9 of 12
Quote:
Originally Posted by DOSbox-gamer View Post

The Core i7 supports hyperthreading (aka HT); the i5 does not. HT lets your system run extra threads per processor; in essence, a Core i7 system has 4 actual cores and 4 'virtual' cores. Right now, very few programs can take advantage of these 4 'virtual' cores, but in the future (2-3-5 years), HT use will easily become common (for heavy-duty apps, mostly).

HyperThreading is more marketing than anything else. Only one thread can run on one core, no matter what. Hyperthreading just speeds up context switching between threads sharing time on a core. 8MB of cache, though, is not often enough to cache eight threads. So this is why the speed bonus of i7 is not 10% over i5, but instead is somewhere between 5 and 10%.
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post #10 of 12
Hey everyone,

I am have been researching the i5 vs i7, and there is a fair bit of info on the PC side. Try this link for example for benchmarks and good info: http://www.hardwarecanucks.com/forum...review-15.html

Especially pay attention to how the i5 and i7 SMOKE the core2 duo -

I will probably spring for the i7. The HT will be worth the extra couple hundred bucks in the long run - thought the i5 is no slouch either. No one who uses the iMac for gaming, encoding, pro apps etc should even think about skimping and going with the core2 duo - not after seeing those benchmarks!

Go i7!
post #11 of 12
Looking at Intel's Processor Finder, the i5 in question is the i5-750 (actually the only i5) and the i7 is the i7-860 which is somewhere between the i7-920 and the i7-870 (obvious, eh? - not!).

Looking at these processor specs, the i7-870 is obviously better than the i7-860 by 0.13MHz. Looking at the performance between these two i5 and i7-920, on x264 encoding, it's approx. 28% faster, on the RAR operation, it is more like 9% faster. Naturally the i7-860 should be slightly faster still, approaching the i7-870's results.

Looking at the processor finder again, the E8400 is probably slightly quicker than the Core2Duo in these new iMacs, because it has 1333MHz front side bus, while the E7600, is the 3.06MHz chip with a 1066MHz bus. Also, it has only 3MB L2 cache, compared to 6MB. The E7300, is the 2.66MHz flavour of the E7600, so performance will be better than that chip but probably worse than the E8400.

As Munch said, there's no competition based on these two benchmarks: an i5 or i7 is going to 'smoke' a C2D.

For those wondering i5 vs i7, hyperthreading is going to help where you are CPU limited. If you are GPU or RAM limited, or I/O limited, having the HT tech won't give a noticeable boost, but most applications are approaching multi-threading aware, especially high end editing and image processing where the maths involved are intense. Being able to process in parallel complex operations will benefit with more cores, virtual or otherwise. With respect to a real/virtual core, you have a single hardware core say and the running thread can stall, having HT means that another thread can pick up and use the hardware core with a lower hit for the context switch of the thread.

Just my two peneth, hope it helps.
Cheers
Moo

Edit: aah I see more benchmarks, my comments above refer to the first two :o)
post #12 of 12

I know this is an old thread but I thought I would pipe in regarding the OP's intention to use Logic Pro.

 

Logic Pro, as shown by a special benchmark Logic project, makes good use of multiple cores and Hyperthreading. When you stop and think about the tons of processes a music production application has to do at the same time, the more threads the merrier!

 

Check this forum:

http://www.gearslutz.com/board/music-computers/371545-logic-pro-multicore-benchmarktest.html

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32GB iPad WiFi. 15" MacBook Pro 2.4GHz Core2 Duo/6GB/200GB. MacBook 2.4GHz Core2 Duo/2GB/200GB. 8GB iPhone 3G. In memoriam: my Sawtooth "Frankenmac" with dual 1.3GHz G4/2GB/360GB striped...
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