[Boochie]

I'd been having some display issues with my older iMac, and I got the damage today from the Apple store - it needs both a new logic board and display backlight. Total cost getting steep to fix a 3 year old computer. The new Retina iMacs sure are appealing. Here's my question though. Practically speaking, will the i5 configuration available in the stores be faster than what I have right now? It seems that I can only get the i7 through the online store, and that would require rather more patience than I have. Main usage would be typical stuff, plus some occasional graphics intensive gaming (Civ 5, CoD MW, etc.) and a lot of Photoshop.

Thoughts?

[OreoCookie]

A new Retina iMac would be faster, especially if you opt for an SSD (which you should!).

[P]

CPU: 2011 27" iMac is a Sandy Bridge 3.4 GHz, max turbo 3.8. Retina i5 is Haswell 3.5GHz, max turbo 3.9. but you miss the Hyperthreading. The difference will be too small to notice, as Haswell has some IPC improvements to compensate for the lack of HT.

GPU: 2011 iMac is an HD 6970M, which is Barts Pro, which is a desktop 6850. Retina i5 is an M290X, which is Pitcairn XT, which is desktop 7870. That is a real step up for the Retina model. I'd say that its something like 75% faster in most cases, but looking through benches, it seems that the gap is bigger than that at high resolutions. It will be noticeably faster, in any case.

The rest of the system depends mostly on whether you have an SSD or not. I think the Retinas come with a Fusion Drive setup by default, which should be good enough.

Go ahead with a new iMac. Those repair costs make no sense.

[Boochie]

Thanks for the detailed rundown, P. From some experimentation in the store, even the base i5 "5K" iMac seems considerably more responsive poking around iPhoto, iTunes, iMovie, etc. It would be about $1000 to fix my old computer, which is an awful lot for something already 3 years old. Well, fun times await, after I properly back everything up...

[reader50]

What is wrong with the motherboard on your old iMac? You could hand it down to someone, and use an external display to work around a backlight issue. Depending on what the motherboard issue is.

[Boochie]

There are two issues I've been having with the thing (which got worse after my AppleCare expired over the summer, coincidentally) - the display flickers from time to time, and sometimes the display will go black (though the computer is still on). They ran diagnostics on it for a day, and said that the flicker was due to a bad backlight, and the display going black was because of a faulty connection between the main controller board and (presumably) the GPU. It was happening earlier this year, and I'm kicking myself for not dealing with it while AppleCare was still in effect. It wasn't happening often enough at the time to rise about the complacency threshold required to lug the thing to the store.

Originally Posted by reader50 

What is wrong with the motherboard on your old iMac? You could hand it down to someone, and use an external display to work around a backlight issue. Depending on what the motherboard issue is.

[P]

Ars has posted an early preview of the Retina iMac gaming, including GPU-Z screens. It is indeed "Tonga", it has 32 CUs and it runs at 850 MHz. This makes it something like a desktop R9-285, which is certainly not shabby - it is very similar to one of the D700 GPUs in the top Mac Pro.

[prl99]

Boochie, order through the Apple Store. Your customized iMac will be at your house before you know it. I'd get the i7 CPU for $250 more. It will be worth the cost in the coming years and will help your iMac last longer. I'd add as much RAM as possible but you can get that later from MacSales or another reputable vendor. Add another $250 for the upgraded graphics card and you'll be able to play games and edit movies a lot faster. As for a disk drive, it depends on how much data storage you need and what you're ultimate use for this iMac will be. I'm looking at a Thunderbolt-2 RAID setup, getting 256GB or 512GB flash storage. Remember, it's very difficult to open the latest iMacs, especially this one, for anything other than RAM. Get what you'll want for future use now. And of course get AppleCare. It is worth it and if you would have taken it in before it expired, you wouldn't be asking which iMac to get (don't feel bad, I've done the same thing missing getting service). I had display and disk problems with my early 2009 iMac and ended up replacing the power supply. I also made sure the display was plugged in properly. It now runs fine and the power supply was only $50 or so. Good luck and happy shopping.

[DCJ001]

Originally Posted by P 

CPU: 2011 27" iMac is a Sandy Bridge 3.4 GHz, max turbo 3.8. Retina i5 is Haswell 3.5GHz, max turbo 3.9. but you miss the Hyperthreading. The difference will be too small to notice, as Haswell has some IPC improvements to compensate for the lack of HT.

GPU: 2011 iMac is an HD 6970M, which is Barts Pro, which is a desktop 6850. Retina i5 is an M290X, which is Pitcairn XT, which is desktop 7870. That is a real step up for the Retina model. I'd say that its something like 75% faster in most cases, but looking through benches, it seems that the gap is bigger than that at high resolutions. It will be noticeably faster, in any case.

The rest of the system depends mostly on whether you have an SSD or not. I think the Retinas come with a Fusion Drive setup by default, which should be good enough.

Go ahead with a new iMac. Those repair costs make no sense.

True. But the Fusion drive can be swapped for a 256GB flash storage (solid state) drive for the same price.

[DCJ001]

Originally Posted by Boochie 

Thanks for the detailed rundown, P. From some experimentation in the store, even the base i5 "5K" iMac seems considerably more responsive poking around iPhoto, iTunes, iMovie, etc. It would be about $1000 to fix my old computer, which is an awful lot for something already 3 years old. Well, fun times await, after I properly back everything up...

This is true because the iMac probably had a flash storage (solid state) drive. Plus, because it uses a PCIE connection for the drive there is a considerably faster connection than a SATA connection.

[fritzair]

Originally Posted by DCJ001 

This is true because the iMac probably had a flash storage (solid state) drive. Plus, because it uses a PCIE connection for the drive there is a considerably faster connection than a SATA connection.

The 2011 i7 is what I am using and you might be able to find one in great shape second hand. I added a SSD after removing the DVD and the machine is very fast compared to the HD only configuration. I can't speak to your needs but the machine was never slow while using Photoshop. The screen is very nice. Having the better and faster USB 3.0 found on newer iMacs would decrease the TimeMachine lag effect during the backup process but I am using a external FW and since I added that drive I don't see the lag anymore.
Sometimes we get caught up in the numbers game which Apple and all of the vendors play. I know eventually the system software or the new 'Next Best Thing' will make the upgrade mandatory, but you may be able to wait a few years. In the mean time, 4K monitors and video systems prices will continue to fall and other faster storage solutions will appear.
Are there printers which print to the 4K resolution at 17" widths (larger format paper)? Or do you prefer the 4K for gaming?

[Boochie]

Originally Posted by prl99 

Boochie, order through the Apple Store. Your customized iMac will be at your house before you know it. I'd get the i7 CPU for $250 more. It will be worth the cost in the coming years and will help your iMac last longer. I'd add as much RAM as possible but you can get that later from MacSales or another reputable vendor. Add another $250 for the upgraded graphics card and you'll be able to play games and edit movies a lot faster. As for a disk drive, it depends on how much data storage you need and what you're ultimate use for this iMac will be. I'm looking at a Thunderbolt-2 RAID setup, getting 256GB or 512GB flash storage. Remember, it's very difficult to open the latest iMacs, especially this one, for anything other than RAM. Get what you'll want for future use now. And of course get AppleCare. It is worth it and if you would have taken it in before it expired, you wouldn't be asking which iMac to get (don't feel bad, I've done the same thing missing getting service). I had display and disk problems with my early 2009 iMac and ended up replacing the power supply. I also made sure the display was plugged in properly. It now runs fine and the power supply was only $50 or so. Good luck and happy shopping.

Great advice. It is done.

[cjrivera]

Boochie, just wondering, what model year/screen size is your older (broken) iMac?

[Boochie]

Originally Posted by cjrivera 

Boochie, just wondering, what model year/screen size is your older (broken) iMac?

2011 / 27". I think it knows that I don't love it any more - on top of the screen going black from time to time, now the left side of the screen is noticeably darker than the right.

[Boochie]

An update - picked up the new iMac yesterday. Unbelievable! Almost instantaneous boot with the SSD, and the screen, oh the screen. Seeing it in a brightly lit store with fluorescent lights doesn't do justic to how amazing it looks in the typical lighting conditions in a home. It's a massive screen on which the text looks like a printout.

[Mike Wuerthele]

Originally Posted by fritzair 

Are there printers which print to the 4K resolution at 17" widths (larger format paper)? Or do you prefer the 4K for gaming?

Larger format printers are available. The resolution is trivial for printers -- 300DPI has been available since the dawn of consumer-level laser printing.

Several Epson models, including this one, will do 17x22 prints:
http://www.amazon.com/gp/product/B00...SIN=B002PLQ7LI

(I'm sure there's cheaper, or by other manufacturers, this is just the first one I found)

[OreoCookie]

Originally Posted by Mike Wuerthele 

Larger format printers are available. The resolution is trivial for printers -- 300DPI has been available since the dawn of consumer-level laser printing.

Just a small qualification: for black and white you are right, but usually colors are mixed by varying the density of the printed. This substantially reduces the resolution in color reproduction. That's why photo printers come with 8-10 inks which have lower-density color inks. Dye sublimation printers, though, are able to mix colors the proper way, but it seems to me that they're not as popular as they used to be.

[Sanjiv Sathiah]

One thing to keep in mind when choosing between a Core i5 and Core i7 desktop chips as used in the iMacs is that the Core i5 quad-core parts do not support Hyperthreading, whereas the Core i7 parts do. If you can afford the extra $$$ it is definitely worth upgrading, especially if you use pro apps lik Aperture, Logic and Final Cut Pro.

[Sanjiv Sathiah]

Hyperthreading doubles the number of instructions per clock cycle per core that th chip is able to process by creating ''virtual cores" that Mac OS X recognizes. Your Mac will "think" that it is addressing 8 cores instead of just the 4 physical cores.

[P]

Not really... A better way to think of Hyperthreading is like this: the front end of your CPU fetches instructions and tries to figure out what they will do, and then puts them in a list of things to be done. Then a piece called the scheduler sends those instructions out to be executed. It can issue several issues at the same time, so it must take care that it only issues instructions that do not depend on each other.

Hyperthreading means that the scheduler gets two lists to choose from. It has the same number of execution units to send them to, but it has a greater chance of finding instructions to issue in parallel. In practice, this can get you something like 20% more performance if there are enough threads to execute. Herein lies the rub. If your computer has 4 or fewer threads that need work, HT does nothing. This is why it is more useful on dualcores - it is more likely that you have 3 threads to work with than that you have 5, so HT makes a difference more often.

[reader50]

When I do a video rip on my 8-core Mac Pro, with hyperthreading enabled, Activity Monitor shows total CPU usage above 1500%. It's getting darn near the full doubling offered by the two virtual cores. Either Xeons have extra ALUs / FPUs per core, or Handbrake is doing a great job issuing threads with non-identical resource requirements.

[P]

Really? Because when I run Handbrake, it limits itself to 4 cores, and I have HT as well. Admittedly not the latest version, but honestly I wonder if running 2 logical threads per core would lead to cache pressure in that case.

(No, the Xeons don't have more execution units. Intel has two core designs, but the small one is only used in the Atoms and the like, none of which Apple uses)

[Mike Wuerthele]

I use handbrake heavily, and on my recored 1,1 Mac Pro and a 2012 i7 Mac Mini, never had any problems hitting all threads.

[P]

The old pre-Nehalem Mac Pro does not have Hyperthreading at all, so it should use all logical cores. The Mac mini should, IMO, work the same as my Lynnfield iMac, but maybe there are some differences in the core design that makes HT more useful on later core designs. Sandy Bridge introduced a uop cache, which means that the decoder bandwidth is not so limiting anymore, and removed some limitations in retire bandwidth, so maybe running more than one logical thread per core might be useful.

Googling "handbracke hyperthreading" opened up a rabbit's hole of benchmarks, people playing with settings and disabling HT to get better performance. Clearly this is not a settled issue.

[Mike Wuerthele]

Original modded mac pro with physical cores included for reference

[reader50]

2009 Nehalem Mac Pro here. Handbrake 0.9.9

I only went by Activity Monitor. Didn't benchmark by transcoding the same file with HT on/off. I'll check this the next time.