Finally bought a 5k but something concerns me

[AlexGraphicD]

After almost one year of research in forums and google and thorough study of each model specs I decided to pull the trigger and buy a used 27 5k from eBay, even though that I had reached to a conclusion that it would be better if I waited for the rumored Kaby lake refresh as it would be considerably superior to the current line.

But the price on eBay was very tempting, a 2TB Fusion, m395 total price $1,700 including Apple care until October 2018!! (Fusion was not my first choice though, I'd prefer 512 SSD, maybe in the future if they do a serious refresh I'll sell this one to get pure SSD).
While other similar used macs come only with 1TB fusion or 1TB HDD in that price range and with lower gpu cards.

The machine is in near perfect condition without noticeable flaws or scratches in the screen and the guy was so generous that he even brought it in my house as he was driving by on the same day I purchased it.

Only thing that kinda worries me a bit is that it seems that there is a slight noticeable lag when scrolling safari and other apps, and I don't know if that is perfectly normal or is part of things that I have read that for the 5k you need the top gpu m395x to have the smoothest experience with the graphics.
My uses are web design (WordPress, illustrator, Photoshop, indesign) and heavy browsing, casual video editing in iMovie and FCX. No 3D rendering or gaming at all.

Any thoughts on your own experience with the different gpu models and if the m395 is sufficient enough to push all those pixels on the screen smoothly?

 

[maflynn]

Only thing that kinda worries me a bit is that it seems that there is a slight noticeable lag when scrolling safari and other apps

I don't notice any lagging on my iMac. I have the same configuration an M395, 2TB Fusion drive

I have read that for the 5k you need the top gpu m395x to have the smoothest experience with the graphics.

No you don't. Maybe for playing games but not for normal usage.

 

[1050792]

The need of the top end GPU is a lie, all of them perform exactly the same besides in 3D applications. There is lag in all of the iMacs with a 5K display especially when having lots of apps open you start to notice mission control and scrolling lag, you can try to put the apps to open in lower resolution mode so they wont use lag as much but as when everything is in retina mode there will always be a slight lag. People who say there is none either are trying to defend their purchase or they dont notice it while in normal usage.

 

[colodane]

Given the specs, the price you paid, your seemingly good relationship with the seller, and the Apple Care warranty valid for almost 2 years, I'd say you made an excellent purchase !!

Don't sweat the 395 vs. 395X. Only difference is the graphics memory, which won't be a factor for normal usage. Only comes into play for games, 3D modeling, etc.

You are in an excellent position. Relax, enjoy learning about and using your new iMac, use the Apple Care if it is ever needed. Then, after a year or two, you can upgrade to a newer model if and when Apple announces something that excites you.

 

[maflynn]

The need of the top end GPU is a lie, all of them perform exactly the same besides in 3D applications.

If you want to play games, then the M395X is a definite, but as I mentioned I'm very happy with my iMac

 

[1050792]

If you want to play games, then the M395X is a definite, but as I mentioned I'm very happy with my iMac

I meant for normal usage there is no need for the top end GPU as some people say, as it makes absolutely no difference in the UI of macOS.

 

[AlexGraphicD]

Given the specs, the price you paid, your seemingly good relationship with the seller, and the Apple Care warranty valid for almost 2 years, I'd say you made an excellent purchase !!

Don't sweat the 395 vs. 395X. Only difference is the graphics memory, which won't be a factor for normal usage. Only comes into play for games, 3D modeling, etc.

You are in an excellent position. Relax, enjoy learning about and using your new iMac, use the Apple Care if it is ever needed. Then, after a year or two, you can upgrade to a newer model if and when Apple announces something that excites you.

You're absolutely right. I got a great machine in a very good price.
My feeling for the lag would be more like the difference when you're watching a video in 30 vs 60 fps. 60 fps is so much more smooth in the eyes and that's what I expected from scrolling in safari. I think in my 2010 iMac that I have overseas, scrolling was smoother indeed from what I remember or maybe that's a wrong impression I have.

 

[johnnyturbouk]

I second the notion about smooth experience of my iMac 5k. The only time I notice a serious lag is when I play CnC contra with 5k resolution via parallels, if I drop the graphics down and close chrome (usually have 10+ windows open), any lag issues are swiftly resolved.

Did you set up as new or restore from an old backup? Having used the same master backup since leopard, my last iMac was really buggy until I wiped and installed the os as a clean install, And subsequently worked absolutely fine.

Have you tried an smc / nvram reset.

Failing a clean install and the other basic troubleshooting measures mentioned, I would contact apple care. Sorry for being the cynic, but There is always the possibility (despite how remote) that there may have been a hardware issue, which may have been a reason for the sale. I would rather be safe than sorry. Keep an explicit log of the issues, resolution tried, and who you have spoken to in case you need to dispute the item.

 

[AlexGraphicD]

I second the notion about smooth experience of my iMac 5k. The only time I notice a serious lag is when I play CnC contra with 5k resolution via parallels, if I drop the graphics down and close chrome (usually have 10+ windows open), any lag issues are swiftly resolved.

Did you set up as new or restore from an old backup? Having used the same master backup since leopard, my last iMac was really buggy until I wiped and installed the os as a clean install, And subsequently worked absolutely fine.

Have you tried an smc / nvram reset.

Failing a clean install and the other basic troubleshooting measures mentioned, I would contact apple care. Sorry for being the cynic, but There is always the possibility (despite how remote) that there may have been a hardware issue, which may have been a reason for the sale. I would rather be safe than sorry. Keep an explicit log of the issues, resolution tried, and who you have spoken to in case you need to dispute the item.

It had sierra on it so I did a clean install and downloaded El Capitan that I had on my AppStore account and then made an upgrade to sierra. I didn't do any restore from backup.

I don't experience any other issues or any serious lag, but I will contact Apple care just to be sure but first I'll try the smc reset.

 

[andy9l]

Remember, you have purchased an all-in-one that pushes a mobile GPU to run a 5K screen. Some lag is to be expected.

We bought the current 3.3GHz model (top range without customisation) straight from Apple several months ago and I do notice the odd lag spike on sites like Facebook etc., or Mission Control / Time Machine. I'm comparing to a £1.5K PC tower at 4K and a smaller rMB, so it's not really fair as the PC has 3-7x better performance depending on your choice of benchmark and the rMB has far, far fewer pixels to push!

Having also previously owned and returned a 2014 M295X 5K iMac, I can assure you things have improved massively. The earlier M295X GPUs were reaching absurd temperatures under load, and there were graphical glitches all over the shop.

Enjoy the iMac, the lag will likely improve with future updates. Honestly, the graphics performance improvements over the past 18 months have been dramatic, particularly on these iMacs. That said, any machine will always be limited by its weakest part - in the case of a 5K iMac, that's the graphics card.

@apppen1 sums it up really well.

 

[1050792]

Remember, you have purchased an all-in-one that pushes a mobile GPU to run a 5K screen. Some lag is to be expected.

We bought the current 3.3GHz model (top range without customisation) straight from Apple several months ago and I do notice the odd lag spike on sites like Facebook etc., or Mission Control / Time Machine. I'm comparing to a £1.5K PC tower at 4K and a smaller rMB, so it's not really fair as the PC has 3-7x better performance depending on your choice of benchmark and the rMB has far, far fewer pixels to push!

Having also previously owned and returned a 2014 M295X 5K iMac, I can assure you things have improved massively. The earlier M295X GPUs were reaching absurd temperatures under load, and there were graphical glitches all over the shop.

Enjoy the iMac, the lag will likely improve with future updates. Honestly, the graphics performance improvements over the past 18 months have been dramatic, particularly on these iMacs. That said, any machine will always be limited by its weakest part - in the case of a 5K iMac, that's the graphics card.

@apppen1 sums it up really well.

I don't think that is safe to say, mobile GPU improved a lot in recent years so there is no excuse to say it's the GPU fault that can't run the 5k display, but apple's fault for not optimizing their OS for the Hardware graphics-wise.

 

[andy9l]

I don't think that is safe to say, mobile GPU improved a lot in recent years so there is no excuse to say it's the GPU fault that can't run the 5k display, but apple's fault for not optimizing their OS for the Hardware graphics-wise.

Never said it can't, only that it's limited in the performance it can offer.

In my opinion, Apple have done a stellar job in optimising macOS - the hardware Apple uses in its popular consumer computers is low-mid range, and yet even some of their older machines offer some of the best HiDPI experiences currently available.

 

[cynics]

Lag can be subjective and hard to describe (what is a slight lag for you may not be noticeable to someone else, or seem worse). You might have want to do a PRAM and SMC reset now that it's all set up to see if that makes a difference.

 

[AlexGraphicD]

Lag can be subjective and hard to describe (what is a slight lag for you may not be noticeable to someone else, or seem worse). You might have want to do a PRAM and SMC reset now that it's all set up to see if that makes a difference.

Yes definitely agree on that. That's why I said it may be my impression and not an actual lag of the computer.

 

[joefrank64k]

FWIW: I just bought a late 2015, 27", 3.3, 2TB Fusion, 32GB, M395 iMac. I set it up as a new iMac, and it's running Sierra.

There is ZERO lag when I'm scrolling in Safari, or Word, or Pixelmator, or whatever.

I'm coming from a late 2010 11" MBA, so know lag when I see it

 

[AlexGraphicD]

FWIW: I just bought a late 2015, 27", 3.3, 2TB Fusion, 32GB, M395 iMac. I set it up as a new iMac, and it's running Sierra.

There is ZERO lag when I'm scrolling in Safari, or Word, or Pixelmator, or whatever.

I'm coming from a late 2010 11" MBA, so know lag when I see it

Maybe the added ram that you got is the reason why you see zero lag?
I have the base 8gb ram.

 

[nambuccaheadsau]

The only time I notice any sort of lag is if the backup hard drive running SD is booted, and I overlook going into System Preference > Startup Disk and manually selecting the internal Flash storage drive. Even whilst selected on restart using Option, it lags on boot and some apps. Goes from the normal 12 second to 37 seconds before the loading bar appears.

Seems to confuse it a little. Hope that helps.

 

[andy9l]

Maybe the added ram that you got is the reason why you see zero lag?
I have the base 8gb ram.

RAM will not impact graphics/animation performance unless you're maxing it out and heavily swapping to disk - even then it shouldn't impact GPU performance.

You both have the same iMac, you both are getting the same experience but with different expectations/perceptions.

 

[joema2]

...you have purchased an all-in-one that pushes a mobile GPU to run a 5K screen. Some lag is to be expected....any machine will always be limited by its weakest part - in the case of a 5K iMac, that's the graphics card...

It was my understanding the GPU is not "running the 5k screen", especially for 2D operations like scrolling. Rather 2D operations are often done by the CPU. There is significant overhead to transfer data to the GPU's memory. This may be worthwhile for a compute-intensive 3D graphics operation, but not necessarily a 2D operation.

You can see how minimal the GPU benefit is for 2D operations by enabling and disabling GPU acceleration in Adobe Lightroom. For some tasks invoking GPU acceleration slows things down.

This article is several years old but it shows that using GPU acceleration for 2D operations can be slower than just using the CPU: https://www.cocoawithlove.com/2011/03/mac-quartzgl-2d-drawing-on-graphics.html

Re the GPU being so weak on the 5K iMac, some benchmarks show it's nearly as fast as a single D700 in the nMP. See attached file. Entire video comparing performance of a 5k iMac to a 6-core nMP and a custom-built Hackintosh:

 

[mpe]

I have experienced at least some UI lag (especially in mission control but elsewhere too) in all retina Macs I worked with. Non retina macs have been better. My work iMac (M395X) lags in Exposé on the primary screen but not on the external thunderbolt display
(1440p)

I remember UI lag was quite terrible when they come with hidpi in Macbook Pro back in OS X Mavericks and improved in recent versions of macOS but it is still there.

It has little to do with GPU, it is almost certainly software inefficiency in inheritely poor graphics stack.

M395 is quite decent GPU. There is very little or no difference between GPUs in Macs. OS/Core Graphics/GL/Quartz is most likely the culprit.

It makes no sense to buy faster GPU with hope that the UI will be more responsive. In fact a little known fact is that M390 is slighty faster at pixel speed than M395 due to faster clockspeed. The later is obviously faster in 3D due to higher amount of units.

 

[andy9l]

*snip*

To drive a 5K screen at 60Hz, my understanding is that these 5K iMacs rely directly on the GPU using some weird, hacked internal connector. At least, that's what reportedly happened with the 2014 models.

The graphics cards are mobile GPUs and no matter what way you cut it, they will never come close to desktop class GPUs of the same era. They should be and are, however, more than enough for basic usage in 5K or more advanced 3D applications like games in 1440p.

 

[joema2]

...you have purchased an all-in-one that pushes a mobile GPU to run a 5K screen. Some lag is to be expected....any machine will always be limited by its weakest part - in the case of a 5K iMac, that's the graphics card...To drive a 5K screen at 60Hz, my understanding is that these 5K iMacs rely directly on the GPU using some weird, hacked internal connector...

The 2016 MBP 15" with 2.2Ghz i7 has no discrete GPU whatsoever, not even a mobile one. Yet a 2017 MBP can drive its native 2880 x 1800 display plus two 5k displays simultaneously. This was demonstrated by Phil Schiller:

If the M395X *mobile* GPU of the 2015 iMac is too weak to push all those 5k pixels around, how does the 2016 MBP with no discrete GPU drive two 5k monitors plus its native 2880x1800 display? Maybe the GPU is *not* responsible for all that 2D manipulation such as scrolling and "bit block transfers".

 

[Zwopple]

The 2016 MBP 15" with 2.2Ghz i7 has no discrete GPU whatsoever, not even a mobile one. Yet a 2017 MBP can drive its native 2880 x 1800 display plus two 5k displays simultaneously. This was demonstrated by Phil Schiller:

If the M395X *mobile* GPU of the 2015 iMac is too weak to push all those 5k pixels around, how does the 2016 MBP with no discrete GPU drive two 5k monitors plus its native 2880x1800 display? Maybe the GPU is *not* responsible for all that 2D manipulation such as scrolling and "bit block transfers".

The MBP w/15" integrated GPU you're talking about is the 2015 model not the late 2016 model. The main issue with 5K displays is not the GPU it's that they need around ~23gb/s bandwidth to drive it at and Thunderbolt 2 only provided 20gb/s. The 2016 models all have USB-C Thunderbolt 3 which provide 30gb/s as well.

The late 2016 13" models without a dedicated GPU can only drive one 5K display and their own internal display due to the GPU bandwidth lacking while the 15" models can drive two 5k's and their internal display.

 

[saberfi]

Oh no...!

I've been lurking the forums while awaiting for the refreshed iMacs for quite some time, and I recall seeing you, AlexGD, also patiently waiting.

And now you've got yourself a machine! I'm starting to feel quite alone.

 

[andy9l]

The 2016 MBP 15" with 2.2Ghz i7 has no discrete GPU whatsoever, not even a mobile one. Yet a 2017 MBP can drive its native 2880 x 1800 display plus two 5k displays simultaneously. This was demonstrated by Phil Schiller:

If the M395X *mobile* GPU of the 2015 iMac is too weak to push all those 5k pixels around, how does the 2016 MBP with no discrete GPU drive two 5k monitors plus its native 2880x1800 display? Maybe the GPU is *not* responsible for all that 2D manipulation such as scrolling and "bit block transfers".

That's a 2016 MacBook with discrete GPU that is being demonstrated, not the 2015 model you're referring to.

No-one is claiming that the GPU is *too* weak, only that it is indeed a relatively weak card for a 5K desktop machine in 2017. There's a difference, and it hugely depends on personal use cases too. There's a reason you can choose to upgrade the GPU on Macs.

The MBP w/15" integrated GPU you're talking about is the 2015 model not the late 2016 model. The main issue with 5K displays is not the GPU it's that they need around ~23gb/s bandwidth to drive it at and Thunderbolt 2 only provided 20gb/s. The 2016 models all have USB-C Thunderbolt 3 which provide 30gb/s as well.

The late 2016 13" models without a dedicated GPU can only drive one 5K display and their own internal display due to the GPU bandwidth lacking while the 15" models can drive two 5k's and their internal display.

Very true regarding bandwidth. I would love to see the performance of a base 2016 13" MBP running two 4K displays...