Did you have hard time make the decision which iMac to buy, which model to choose, what are their differences, read this guide
Name: iMac late 2009 model
This model was introduced 20.10.2009
Photo Credit: niiconn

There are four models available, the differences are:

• 21.5 inches, 3.06GHz Intel Core 2 Duo, 500GB hard disk drive, NVIDIA GeForce 9400M, price 1,199$
• 21.5 inches, 3.06GHz Intel Core 2 Duo, 1TB hard disk drive, ATI Radeon HD 4670 with 256MB memory, price 1,499$
• 27 inches, 3.06GHz Intel Core 2 Duo, 1TB hard disk drive, ATI Radeon HD 4670 with 256MB memory, price 1,699$
• 27 inches, 2.66GHz Intel Core i5 (Quad Core), 1TB hard disk drive, ATI Radeon HD 4850 with 512MB memory, price 1,999$

Every model includes 4GB (SO-DIMM) DDR3 memory, 8x double-layer SuperDrive, integrated WiFi and Bluetooth, the 21.5 inch models support display resolution up to 1920 x 1080 pixels, while the 27 inch support up to 2560 x 1440 pixels, wireless keyboard and mouse, iSight camera ( more detailed specs bellow )

Pictures

Description of the model

This is one of the oldest and most innovative computers by Apple. First introduced in August 1998, this computer touched the hearts of critics, fans and average users with its all-in-one design and simplicity. Over the years this model was continuously redesigned and upgraded, but the original idea remained – a computer which is ready for work after you plug in the power cable. This year Apple introduced the latest till now iMac models, which are trying to became even powerful as the Mac Pro with its i5 and i7 Quad Core processors.

Full Specifications

Processor:
The first three iMac models comes with the 3.06GHz(E7600) Intel Core 2 Duo processor with 3MB shared L2 cache and 1066MHz Front Side Bus, upgradable to 3.33GHz(E8600) with 6MB shared L2 and 1333MHz Front Side Bus. The last and most expensive iMac holds inside 2.66GHz(750) Intel Core i5, upgradable to 2.8GHz(860) Intel Core i7 processors with 8MB shared Level 3 cache, both of them are Quad Cores CPUs, so if you buy this model you will own one of the fastest processors available these days on the market. If you want to see more details specifications of the processors, look at the Intel’s site

Memory:
Like every of the new Macs this one too comes with DDR3 memory (SO-DIMM type), but can hold up to 16GB of memory in its 4 slots. The current models have two 2GB SO-DIMMs installed. Its an interesting thing to say that the DDR3 memory will achieve bigger performance when used with i5 or i7 processors than with the Core 2 Duo.

Hard Disk Drive and Optical Drive
Except the cheapest model, which comes with 500GB hard drive, all of the others iMacs are with 1TB hard disk drives, both upgradable to 2TB. All of them are Serial ATA and working at 7200 RPM.

Video Card:
I am little disappointed that the basic iMac comes with GeForce 9400M, because although its the slowest model, still it has a wonderful components, which stand at higher level than this chipset, but it seems that nobody who will be editing video will buy the entry level model, which is logical by the way because of the smaller display size too. But none the less this model is ideal for work/home solution. The more expensive iMacs comes with ATI Radeon chipsets – HD 4670 with 256MB memory and HD 4850 with 512MB for the Quad Core model, both the mobility version of the chipset (meaning lower speeds than the desktop version), but due to this more powerful graphic cards, these models are prone to screen flickering because of the bigger heat output from this chipsets, Apple released an update, which is fixing this issue, but most of the users in the support forums are still experiencing the problem, you can keep up with the latest news about this bug at the Apple’s support forums

Note: The scores below are for FPS(frames per second). For normal play, the FPS need to be at least 20. The scores are not 100% accurate and may vary.
Performance scores for GeForce 9400M

• Crysis. 1024×768, medium settings, AA/AF off: 13.2 FPS
• World in conflict. 1024×768, medium settings, AA/AF off: 11 FPS
• Quake 4. 1024×768: 58.7 FPS
• Call of Duty 4. 1280×800, optimal settings: 23.9 FPS, falls to 11 in complex scenes
• Team Fortress 2. 1280×800, max settings, AA 2x, 35 FPS
• Half Life 2. 1280×800, max settings, AA 4x. 31 FPS

Score in 3DMark 2006: 2207 points.
For detailed specifications see NVIDIA’s site

Performance scores for HD 4670 256MB

• Crysis. 1280×1024, High details, 23 FPS
• World in conflict. 1280×1024, Very High details, AA/AF off: 35 FPS
• Quake 4. 1024×768: 154 FPS
• Call of Duty 4. 1280×1024. Medium details. 66.2 FPS
• Team Fortress 2. 1280×1024. Medium details. AA 2x. 69 FPS
• Half Life 2. 1280×1024. High details. AA 4x. 83 FPS

Score in 3DMark 2006: 6995 points.
Detailed specifications of HD 4670(4600 series)

Performance scores for HD 4850 512MB

• Crysis. 1280×1024, High details, 47.7 FPS
• World in conflict. 1440×900, Very High details, AA/AF off: 56 FPS
• Quake 4. 1680×1050: 242 FPS
• Call of Duty 4. 1280×1024. Medium details. 87.1 FPS
• Team Fortress 2. 1280×1024. Medium details. AA 2x. 105 FPS
• Half Life 2. 1680×1050. High details. AA 4x. 116 FPS

Score in 3DMark 2006: 9136 points.
Detailed specifications of HD 4850

Display:
Normal 21.5 inch and huge bad-ass 27 inch LED-backlit glossy displays, these are the available monitor sizes with the late 2009 iMacs, both with 178° viewing angles with 16:9 aspect ratio, millions of colors at every resolution (21.5 inch supports up to 1920×1080 and the 27 inch supports up to 2560×1440), the brightness is 320 cd/m2(21.5 inch) and 375 cd/m2(27 inch). Both are with IPS technology, which is very good, because this kind of displays are superior to the more used (and cheaper) TN technology in the more common consumer monitors. The displays which are using IPS have better viewing angles, faster response time and better picture/color quality, so if you need better than the average display you will be happy owner. In the rare cases when, you need more than one monitor, you can easily plug in another monitor to your iMac through the Mini DisplayPort, because it can support resolution up to 2560×1600 on the external display i.e. high resolution glory at both displays

Audio, Communications and Peripherals:
When you are buying iMac, you have to know that it comes with everything – built-in speakers, built-in camera (iSight), microphone, jacks for headphones and microphone (you will need special types of microphones, to work with the jack or buy an adapter), built-in WiFi ( 802.11n and compatible with 802.11a/b/g ), built-in Bluetooth and Ethernet card. Like the new MacBook Pro models, this mac comes with SD Card slot, and makes the digital camera to computer transfer faster and easier. At the back of the machine, you will find 4 USB 2.0 and one FireWire 800 ports, headphones and mic jacks.

What its in the box

When you buy iMac, you receive everything you need to begin using it ( and for this amount of money you should be ^^ ) – the machine itself, wireless Apple Keyboard( with or without the numeric keypad ), the new Magic Mouse(which by the way is selling really good i.e. its a good product i.e. you are not getting something crappy ), power cord, install/reinstall DVD-s and manuals

So you are thinking of buying the late 2009 iMac, but want to now more then please read the following info

The Good and the Bad

The main pros and cons of the late 2009 iMac models are:
The Good

• All in one, just power it up, and you are good to go
• Really powerful computer
• Stylishly looking

The Bad

• The Price
• There are some problems with the displays, some of the 27 inch models are flickering, arrive cracked or jaundiced
• Only memory and hard disk drive can be upgraded

Upgrade Options

The upgrade is one of the iMac bad sides i.e. after the purchase, you can upgrade only the memory and if you want to change the hard disk then you have to go to the Apple Store. But then again, you receive the iMac with 1TB space (500GB with the first model), which is pretty large and for around 200$ you can buy this Mac-ready Seagate FreeAgent Desk 1.5 TB
external HDD and you will have 2.5TB free hard disk space, which is more than enough. As for the memory – its absolutely easy to change the banks yourself, its a matter of 5-10 minutes. This is a really nice video, which shows you how this can be done

Known Bugs

Although the iMac is a great machine, it comes with problems and I hope Apple is trying everything to fix them, as fast as possible. So now ( 03.01.2010 ) the known problems are:
- flickering display: due to the higher heat levels of the video card, after intensive work, the display begins to flicker. Apple released a patch to fix this issue, but it seems that some users are still experiencing problems ( watch this thread at Apple’s support forum )
- Yellow display – the colors of the display are not reproducing right, thus there is a difference in the warmth of the colors at the top and at the bottom of the screen. See this article for more details.

Performance Comparison

Here is a table, which compares the iMac with some other macs and generic computers

Name	Specs	Score
Mac Pro (Early 2009)	Intel Core i7 950 3.09GHz Quad (8MB L3), 6GB ram	9182
iMac 27 inch	Intel Core i7 860 2.80GHz Quad (8MB L3), 8GB ram	8428
iMac 27 inch	Intel Core i7 860 2.80GHz Quad (8MB L3), 4GB ram	7600
Windows 7, motherboard Acer Aspire M5810	Intel Core i7 860 2.80GHz Quad (8MB L3), 4GB ram	7421
iMac 27 inch	Intel Core i5 750 2.66GHz Quad (8MB L3), 4GB ram	6516
Windows XP, motherboard GigaByte P55M-UD2	Intel Core i5 750 2.66GHz Quad (8MB L3), 3.5GB ram	5758
iMac 21.5 inch	Intel Core 2 Duo E6600 3.33GHz (6MB L2), 4GB ram	4707
iMac 21.5 inch	Intel Core 2 Duo E7600 3.06GHz (3MB L2), 4GB ram	4191
iMac (early 2009)	Intel Core 2 Duo E8235 2.80GHz (6MB L2), 2GB ram	3775
Mac mini (Late 2009)	Intel Core 2 Duo P8700 2.53 GHz (3MB L2), 4GB Ram	3563
MacBook Pro (15-inch Mid 2009)	Intel Core2 Duo P8700 2.53GHz (3MB L2) 4GB Ram	3532
MacBook Pro (13-inch Mid 2009)	Intel Core2 Duo P7550 2.26GHz (3MB L2) 4GB Ram	3261

So, what do you think? The new iMac is a monster right? Its even close to the enormous power of the Mac Pro when you add more memory. So the Quad iMacs will satisfy the needs of intermediate photo/audio/video editor, while the basic models will cover the basic home/office use and you will be able to run the latest game, rip dvd or edit video clip. As you can see the iMacs are beating theirs Windows-using “opponents”, this is because all of its parts are chosen specifically for each other, while the parts of the windows machines are usually chosen only by the price, and some characteristics – they do work and as you can see are showing excellent score, but not optimized for each other, the Windows OS is not able to utilize their full potential, because of the wide variety of hardware which it must support. But from this comes one of the flaws of the iMac – if a faster video card, motherboard or processor arrives, you can’t use them even if the OS allows it, and the windows users can use it right away. But still – do you see yourself upgrading your computer every 3 months or so? I am using 2 year old MacBook and its perfect in terms of speed, the Macs are build to last – give more now, but save in the long run.

For what can be used

• Editing machine: with its four cores and processor using latest and fastest architecture, large display with even bigger resolution, the iMac can be used for audio and video editing
• Home and/or Office: the basic models (21.5 inch) fit perfectly in this category, all in one, easy to use, easy to setup, easy to maintain and will last long in terms of compatibility. The 27 inch model is a little bit of overkill for home use.

Accessories:

I can think of only one:

• External Hard Disk: I am going to recommend this option every time I write a guide for computer using the OSX. If you have important documents, just backup them with Time Machine. The time and frustration which the backup will save you is just priceless.

Conclusion:

What are you looking for?
- Performance? – the iMac is made to perform, fast CPU and video card, lots of memory and hard disk space, big display.
- Building from scratch? – the iMac is for you, its all in one, no need to buy something else.
- Budget? – if you are looking for the cheapest machine, then the iMac is not for you. Everyone of the Mac computers is not for you ( if you really want a Mac, then consider the Mac Mini ), they are expensive, but for a reason.
- Good looks? – all of the Mac computers are designed to be beautiful and the iMac is not exception. When you see it with your eyes you will fall in love, so beware^^
- Just works? – well right now, the iMacs, even marketed as the ultimate computers, are not! If you want it, wait couple of weeks, for the problems to be resolved, then buy your dream computer. Or look around for the previous model, although they will perform slower, it will be a good deal in terms of price and stability. Price – because the stores will try to free themselves from the old models and mare room for the machines, so it is possible that they give you a nice promotion in terms of money or free upgrades.
- Stability? – the old models will have no or little bugs, because they were on the market for some time now, and their problems are well-known and thus fixed.

If this article had convince you to buy a iMac, you can do it from Amazon
Edit 05.05.2010: the video card info is changed, the 4670 and 4850 ATI Radeon cards used in the iMac, are the mobility version of this chipet

Resources:
More info about performance here