iMac Core 2 Duo versus three older iMacs

Originally posted September 13th, 2006, by rob-ART morgan, mad scientist.
September 22nd, 2006, added more 24" iMac Core 2 Duo results.

This is our first installment of iMac Core 2 Duo performance results. In this segment, we're comparing the 20" iMac Core 2 Duo 2.16GHz model with three older 20" iMacs. In a few days, we will add results from a 24" iMac Core 2 Duo 2.33GHz.

We, of course, expect the 24" iMac to smoke all the other iMacs ever made -- especially with the optional GeForce 7600 GPU (256M) installed. But we're more intrigued by the advantage the "mid-range" 20" iMac might have over its 20" siblings. For example, with less than a 10% faster CPU, the same frontside bus speed, and the same Radeon X1600 GPU, will the iMac Core 2 Duo 2.16GHz be significantly faster than the previous iMac model (Core Duo 2.0GHz)?

We've looked in on discussion groups where owners of G5 iMacs are wondering if it's time to sell their machine and get the iMac Core 2 Duo. In other words, how much speed will they gain for the pain?

CPU intensive GRAPH LEGEND
iMac C2D/2.33 = 24" iMac Core 2 Duo 2.33GHz
iMac C2D/2.16 = 20" iMac Core 2 Duo 2.16GHz
iMac CD/2.0 = Jan 2006 - 20" iMac Core Duo 2.0GHz
iMac G5/2.1 = Oct 2005 - 20" iMac G5/2.1GHz 'iSight'
iMac G5/2.0 = May 2005 - 20" iMac G5/2.0GHz 'ALS'
(All test systems had 2GB of memory)

APPLE iMOVIE HD 6 (Universal Binary)

APPLE iTUNES 6 (UB -- now available in version 7)

MAXON CINEBENCH 9.5 (Universal Binary)

ADOBE PHOTOSHOP CS2 (Rosetta)
We used the new Retouch Artists' Speed Test

GPU intensive GRAPH LEGEND
Mac Pro 3.0 G7300 = Mac Pro 3.0GHz with GeForce 7300 GT (256M)
iMac C2D/2.33 G7600 = 24" iMac Core 2 Duo 2.33GHz with GeForce 7600 GT (256M)
iMac C2D/2.16 G7600 = 24" iMac Core 2 Duo 2.16GHz with GeForce 7600 GT (256M)
iMac C2D/2.16 X1600 = 20" iMac Core 2 Duo 2.16GHz with Radeon X1600 (128M)
iMac CD/2.0 X1600 = Jan 2006 iMac Core Duo 2.0GHz with Radeon X1600 (256M)
iMac G5/2.1 X600 = Oct 2005 iMac G5/2.1GHz 'iSight' with Radeon X600XT (128MB)
iMac G5/2.0 9600 = May 2005 iMac G5/2.0GHz 'ALS' with Radeon 9600 (128M)

STONE DESIGN's iMAGINATOR (UB)

ASPYR DOOM 3 (UB)

ASPYR QUAKE 4 (UB AND MP aware)

MACSOFT UNREAL TOURNAMENT 2004 (UB)
Macologist.org has come up with a new SantaDuck Toolkit that enables dynamic shadows. We ran at Maximum quality with Sound enabled.

MACSOFT HALO UNIVERSAL

You'll notice we used 1024x768 instead of the 20" display's native 1680x1050 resolution in the 3D game tests above. That's so the older iMacs had a fighting chance.

PAGE TWO OF GAMES AT HIGH REZ
Though we don't expect most iMac Core 2 Duo gamers to run at the highest resolution of their 20" (1680x1050) or 24" (1920x1200) iMac Core 2 Duo, we still ran some tests at those settings and compared those numbers to the Mac Pro running a GeForce 7300 and Radeon X1900. If you are interested GO TO THE SPECIAL HI-REZ IMAC GAME PAGE.

WHY ONLY 3GB of RAM?
Why is the Core 2 Duo, a true 64 bit processor, limited to 3GB of memory expansion? According to Intel's description of the 945PM Express Chipset on which the iMac is based, it supports "up to 4GB memory addressability."

Plus, the downside of the 3GB configuration is the loss of the interleaving speed advantage provided by matching pairs. Isn't this frustrating?

CONCLUSION
We did some calculations. The iMac Core 2 Duo 2.16GHz has an 8% clock speed advantage over the iMac Core Duo 2GHz. Yet in our CPU intensive tests, the Core 2 Duo's performance advantage ranged from 10% to 50%. In our GPU intensive tests, the advantage ranged from 10% to 23%. (In the unpublished UT2004 Flyby test, the advantage was 38%.)

That's an impressive performance bump over the previous iMac considering both have the same frontside bus speed, same memory speed, and same graphics processor. We can't wait to see how well the 24" Core 2 Duo does with the optional 2.33GHz clock speed and the GeForce 7600 GT GPU with 256MB of DDR3.

IS IT ALL IN HARDWARE?
We were checking to see if the iMac Core 2 Duo had a newer version of OS X compared to the iMac Core Duo. They both are running 10.4.7, but we noticed that the Core 2 Duo had a later build (8K1106 vs 8J2135a). We also happened to do a "Get Info" on the Radeon X1600 driver (ATIRadeonX1000.kext) and noticed it was a different build, too.

That causes us to wonder if the iMac Core 2 Duo's advantage is strictly due to the processor change or if there are also a few enhancements to the system software as well. Maybe when Apple releases the next iteration of OS X and we have identical builds on both the iMac Core 2 Duo and Core Duo, we'll know the answer.

JUST A CPU SWITCH?
One has to wonder if Apple just pulled the Core Duo out of the socket of the 20" main logic board and plugged in the Core 2 Duo. After all, it has the same Radeon 1600 as the previous model and lacks the FireWire 800 port added to the 24" model.

And it's too bad that the Geforce 7600 isn't an option for the 20" model since I predict it will be the most popular screen size. Apple may think that 17" and 20" buyers have low expectations but I believe they are wrong. I bet they would sell many more iMac Core 2 Duos if the 20" model had the same features and options as the 24" model.

MORE TO COME
Like we said, stay tuned for more test results. We plan to include the 24" iMac Core 2 Duo with optional GeForce 7600 GPU running at low and high resolutions. And, as the opportunity presents itself, we'll post results from other permutations of the iMac Core 2 Duo -- such as the 20" running at 2.33GHz with 256MB VRAM option. Or the 24" running at 2.16GHz with the stock GeForce 7300 GPU.

We may also add some other Macs (like older G5 Power Macs and low-end Mac Pros).

We are also planning to add results from other applications such as Motion 2 and iDVD (encoding). So consider this page a work in progress.

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WHERE TO BUY REFURBISHED or CLOSEOUT iMACS
For refurbished, reconditioned, open box (as well as new) iMacs, check with Small Dog and Power Max. Also look for the "SPECIAL DEALS" link on Apple's online store.