Can OS X handle dual monitors?

[karohan]

Can Macs (w/ OS X obviously) handle dual monitors without any slowdowns? I have noticed that when I run my Macbook Pro mid-2010 i7 with a 24" external, my Expose animations (amongst other things) are slowed down. It's not super, unbearable lag but its significant and noticeable (a little stronger than using the Intel graphics card over the Nvidia). If I repeatedly initiate Expose 5-6 times, it will become smooth like I'm just using the single laptop screen. Why does this occur? Is this a limitation of Macs (my old laptop didn't have this problem, but it was running Linux, so I'm not sure if that affects anything) or is it something that only I am experiencing?

Another interesting revelation is if I disable BeamSync, the animations become a lot smoother with dual monitors (I don't really notice a difference with just the single monitor). Unfortunately, the tearing that occurs is just too much of an issue. But once again, it makes me wonder if its a hardware limitation or just OS X's mediocre ability to handle graphics with dual monitors.

Once again, the Expose lag for example is not enormously gigantic or anything, but it is definitely significant and very noticeable. It is choppy enough that I don't use my second monitor anymore.

 

[GGJstudios]

Can Macs (w/ OS X obviously) handle dual monitors without any slowdowns?

Of course, it can. I use dual displays frequently, with zero impact on performance.

 

[mrchinchilla]

No effect on performance here either.

 

[Heb1228]

It seems that any performance hit from running dual monitors would be because of video hardware rather than the operating system. BTW, I've never noticed any difference in performance when running either single or dual screen setup on this MacBook Pro.

 

[karohan]

Wait, so you don't notice any increased choppiness in Expose when on dual monitors (a choppiness a little stronger than the increased choppiness of using Intel over the Nvidia on the mid-2010 Macbook Pros)?

Do you have Macbook Pro or iMac? Because I'm getting this choppiness on my Macbook Pro.

 

[GGJstudios]

Wait, so you don't notice any increased choppiness in Expose when on dual monitors (a choppiness a little stronger than the increased choppiness of using Intel over the Nvidia on the mid-2010 Macbook Pros)?

Do you have Macbook Pro or iMac? Because I'm getting this choppiness on my Macbook Pro.

I've never experienced choppiness using an external display with my Early 2008 MBP.

 

[Heb1228]

Nope, just tried it and didn't see any difference.

 

[karohan]

Gah, maybe it's just me? Should I take it to a Genius? Is it possible to have a faulty display output or something?

 

[ChefJayPeek]

Gah, maybe it's just me? Should I take it to a Genius? Is it possible to have a faulty display output or something?

What all do you have running? I have been using dual monitors since the Powerbook days, can I make Expose choppy? Sure, if my ram is maxed out.

Post more details about when you try Expose. I notice it most when Time Machine is backing up.

Chef Jay

 

[maflynn]

I've used dual monitors with a variety of Macs, low and high end without any impact on performance or choppiness.

 

[simsaladimbamba]

Gah, maybe it's just me? Should I take it to a Genius? Is it possible to have a faulty display output or something?

What GPU are you using? Use gfxcardstatus to see what GPU is in use, though even on my 2009 MBP with 9400M and 9600M GT I don't have choppy Exposé while using the 9400M, even with 24 windows spread over 12 Spaces using two monitors (1920 x 1200 and 1280 x 1024), unless you mean a slight delay is choppy.

 

[karohan]

Well it's more than a slight delay because the animation itself is choppier as well. And the effect will be visible with as little as one window and with as many as 24. I am running the Nvidia. So it is definitely not contingent on what I am doing on the computer.

In case we just have different opinions on what "choppy" means, I notice if you really quickly initiate Expose 5-6 times or so, the animation will sometimes become silky smooth like I was using a single monitor. That's how I know there's a difference between the usual choppiness and the smoothness it can be.

My resolutions are 1920x1200 secondary display and 1680x1050 primary.

 

[talmy]

It's unquestionably harder on the system driving two displays. You only have to consider that there are twice as many pixels (or more) to update with any full screen(s) animation!

I've seen slowdown to spinning beachballs (!) when I change screen magnification (control+scroll) with an external projector attached, running a Windows 7 virtual machine with programs running, and capturing the whole thing using iShowU HD. This is on a 2.4GHz Aluminum MacBook with 4GB of RAM.

 

[karohan]

It's unquestionably harder on the system driving two displays. You only have to consider that there are twice as many pixels (or more) to update with any full screen(s) animation!

I've seen slowdown to spinning beachballs (!) when I change screen magnification (control+scroll) with an external projector attached, running a Windows 7 virtual machine with programs running, and capturing the whole thing using iShowU HD. This is on a 2.4GHz Aluminum MacBook with 4GB of RAM.

I agree. That's why I thought it would just be a hardware limitation. However:
1. My old laptop which is clearly inferior hardware-wise runs dual displays totally fine. It had an Nvidia 7600 go. So if anything, it suggests to me its more an OS X issue than a hardware issue (but if the other replies suggest anything, it might just be an issue with myself than with OS X).

2. The lag is constant whether I am running intensive programs or not. It's constant. So clearly the load on the computer isn't causing the roughness, unless moving one window is enough to cause it.

 

[snberk103]

...

Another interesting revelation is if I disable BeamSync, the animations become a lot smoother with dual monitors (I don't really notice a difference with just the single monitor). ...

Gah, maybe it's just me? Should I take it to a Genius? Is it possible to have a faulty display output or something?

I'm not sure what BeamSync is, but it seems to me you may want to look at it, instead of blaming the Mac....

 

[karohan]

I'm not sure what BeamSync is, but it seems to me you may want to look at it, instead of blaming the Mac....

BeamSync is part of the OS X operating system. Maybe someone can explain this better than I can, but basically BeamSync is typically automatically activated in OS X. It prevents windows and other graphics from being drawn too fast because if they occur at an FPS too high for the refresh rate of the monitor, you will notice tearing during any sort of motion on your screen. Disabling BeamSync seems to improve the frame rate of animations but like I mentioned, it causes that tearing, which is unacceptable. If you are registered as a developer with Apple and want to see what I am talking about, download/install the Xcode developer tools and look for a program called QuartzDebug to find an option to disable/enable BeamSync. Similarly, if you don't want to download such a large file, you can get the individual program (QuartzSimple) from here:
http://quartzsimple.mac.informer.com/

Once again, BeamSync is a part of OS X and the default setting is the problem. Disabling it improves things, but creates another issue (tearing), which I can't deal with.

 

[Consultant]

I agree. That's why I thought it would just be a hardware limitation. However:
1. My old laptop which is clearly inferior hardware-wise runs dual displays totally fine. It had an Nvidia 7600 go. So if anything, it suggests to me its more an OS X issue than a hardware issue (but if the other replies suggest anything, it might just be an issue with myself than with OS X).

2. The lag is constant whether I am running intensive programs or not. It's constant. So clearly the load on the computer isn't causing the roughness, unless moving one window is enough to cause it.

No, it's not OS X issue unless you want it to be.

List your RAM / specs. Try a flash blocker because you probably have flash running in the background taking up cpu cycles.

 

[jzuena]

I have a mid-2010 i7 MacBook Pro (listed in my sig) driving a 32" cinema display and have been hitting the expose keys as fast as possible and not seeing the choppiness or tearing. I do use the ACD as the main screen when it is connected (2560 x 1600 main display, 1680 x 1050 secondary display) so I don't know if that makes a difference. Using gfxCardStatus, I've left Dynamic Switching turned on, and my system is using the NVIDIA 330M.

 

[snberk103]

BeamSync is part of the OS X operating system. Maybe someone can explain this better than I can, but basically BeamSync is typically automatically activated in OS X.... If you are registered as a developer with Apple and want to see what I am talking about, ...

Thanks for the clarification, and my apologies for making an assumption about BeamSync. Quite often I see people with flaky 3rd party software that causes problems, and then blame the Mac. I jumped to the wrong conclusion in this case.

I'm not a developer, and at this point I have nothing else to add that can possibly help you.... so I wish you luck in finding a solution.

cheers

 

[karohan]

No, it's not OS X issue unless you want it to be.

List your RAM / specs. Try a flash blocker because you probably have flash running in the background taking up cpu cycles.

I'm sorry, I feel like I'm offending people here, but I have a mid-2010 Macbook Pro with the 4 GB RAM and 500 GB 5400 RPM HDD. I have the High-Res display. To clarify again, I have this issue without anything more open than one Finder window, and I've checked the Activity Monitor for phantom processes. The choppiness exists straight after a restart, straight after a reinstall of the operating system, anytime really.

I'm pretty OCD, but regardless, there is definitely a difference in the smoothness of the Expose animation on dual monitors and on single monitors on my computer. If other people really are noticing ZERO difference, which they are saying, that's great. I really hope this isn't an OS X problem because I'm considering dual-booting Linux just to have an enjoyable experience for day-to-day things and keeping the OS X for when I need Photoshop or other particular applications. However, all of you guys mentioning no difference at all is really encouraging because it suggests that my problem is fixable, which always good.

 

[simsaladimbamba]

You could make two/three short video samples via QuickTime X and its screen recording abilities, one with no external display, another with an external display and recording the MBP's screen and another with an external display and recording the external display (you have to do this for that) and either uploading it here as three zipped files (1.14MB each) or any other file sharing service, like http://www.mediafire.com/.

 

[karohan]

You could make two/three short video samples via QuickTime X and its screen recording abilities, one with no external display, another with an external display and recording the MBP's screen and another with an external display and recording the external display (you have to do this for that) and either uploading it here as three zipped files (1.14MB each) or any other file sharing service, like http://www.mediafire.com/.

I initially considered doing that, but screen recording is typically so hardware intensive that the animations will lag on the video just because of that so you won't get an accurate depiction of what I'm talking about. I'll try taking a recording from my iPod Touch and see if that's better.

 

[karohan]

I tried with the iPod Touch but it can't adequately capture what I'm talking about.

 

[simsaladimbamba]

I tried with the iPod Touch but it can't adequately capture what I'm talking about.

Why? Doesn't pointing the lens toward the screen and triggering Exposé suffice?

 

[karohan]

It's really hard to explain what I mean by choppiness, but what might help people compare is: Try the Expose with dual monitors a few times and try it (still on dual monitors) but while mirroring the display. It's definitely choppier a lot of the times when you're on dual instead of mirror.