Update 5/15/2010: Valve released a new patch for Portal on the 13th which resolved the blurriness issue. Please see our update below for for the full details.

It’s been a while since anyone treated Mac OS X as a first-tier gaming platform, so when Valve announced that they would be bringing their Steam service and the Source engine to the Mac, it was big news. After a roughly 2 month beta period for the Mac versions of Steam and the Source engine, yesterday Valve finally released the first wave of their Mac gaming efforts.

As it stands Valve is taking a gradual approach to rolling out their back catalog to the platform. Even though Steam is out and the Source engine has been ported, this week has seen the release of only 1 Source game for the Mac: 2007’s critically acclaimed Portal.

While it’s not the most graphically intensive Source game these days (that title belonging to Left 4 Dead), at this point it’s as good as anything else for looking at the performance of the Source engine under Mac OS X, particularly considering how long it’s been since a game’s original developer did the Mac port. So with that in mind, we went ahead and took a quick look at Portal’s performance under Mac OS X.

As is the case with all of the games on the Source engine, they’re designed to scale up and down fairly well. With modern hardware though, we’re hard-pressed to keep older Source games from achieving runaway frame rates. So Portal performance is somewhat arbitrary – most Macs with a discrete GPU should be able to handle it to an acceptable degree.

The Test

For our test we loaded up our GPU test rig with Mac OS X 10.6.3 in a Hackintosh configuration. As Mac OS X does not currently support either the GeForce GTX 400 series or the Radeon HD 5000 series, we had to step back a bit with our video card choice, settling for a GeForce GTX 285. And while the use of a Hackintosh does technically invalidate our results since it’s not a real Macintosh, based on our experiments we believe that our results don’t suffer in any way for using a Hackintosh, and as such we believe the results to be experimentally valid. But of course, your mileage may vary.

CPU: Intel Core i7-920 @ 3.33GHz
Motherboard: Intel DX58SO (Intel X58)
Chipset Drivers: Intel (Intel)
Hard Disk: OCZ Summit (120GB)
Memory: Patriot Viper DDR3-1333 3 x 2GB (7-7-7-20)
Video Cards: NVIDIA GeForce GTX 285
Video Drivers: NVIDIA ForceWare 197.13
OS: Windows 7 Ultimate 64-bit
Mac OS X 10.6.3 "Snow Leopard"

Image Quality

We’ll start quickly with a look at image quality. Valve is traditionally a staunch Microsoft ally, having built up their services and engines around Windows and DirectX. For the Mac OS X port of Source, Valve had to replace the DirectX backend of Source with Mac-appropriate components, the key of which is OpenGL. Such a change can impact image quality depending on how it’s done.

Portal - Windows. Click to enlarge

Portal - Mac OS X. Click to enlarge.

We have a gallery of screenshots, but for our analysis we’ll stick with comparing in a single set. Going with 2560x1600 with the game at its highest settings and 4xAA/16xAF, to our surprise the images are distinctly different when directly compared. The Mac screenshot is noticeably foggier than the Windows image, and textures appear to be less sharp. It’s not a night & day difference, but the Windows screenshot is distinctly clearer than the Mac screenshot. Without a Windows reference image it would be harder to tell that the Mac screenshot differs this much, but we believe that the difference is great enough that anyone with an eye for details that has ever played Portal on Windows would notice the foggier/blurrier IQ on the Mac.

Now some of this can be explained away due to gamma, since Mac OS X and Windows have different default gamma levels, but gamma could never explain the entire difference. There’s clearly a difference in IQ between the Windows and Mac OS X versions of Portal, and it’s not in the Mac’s favor. It’s by no means bad, but as one person put this when being shown these screenshots “It’s like looking at a magazine scan” when looking at the Mac.


The other half of our quick look is at performance. The Macintosh platform is renowned for being a graphical powerhouse, but this refers to professional/prosumer photography and the like. For gaming, Apple has been slow to include support for new hardware and new driver features (they are just now OpenGL 3.0 compliant) and overall their drivers are more conservative when it comes to performance. Portal is going to be slower, the question is by how much.

We went ahead and ran a timedemo from test chamber 18 and beyond on both the Mac OS X and Windows versions of Portal. We kept the settings cranked up at all times, but varied the resolution between 1280x800 and 2560x1600 to look at different GPU loads. At the worst-case of 2560, the Mac version of Portal runs at only 54% of the speed of the Windows version. That moves to 63% at 1920x1200, and 66% at 1280x800.

Portal – like all Source engine games – is CPU limited when given a powerful enough GPU, and even with just a GTX 285 we can approach that under Windows. Under Mac OS X however, we look to be GPU limited at all times. The framerate never suffers as we’re always averaging more than 60fps, but we can easily turn off MSAA and AF to improve performance if we needed to.

Closing Thoughts

For Source engine enthusaists hoping to see the Mac OS X port of the Source engine meet the high standards of the Windows version, Portal presents a mixed bag. In our limited testing the Mac version of Portal doesn’t significantly suffer for being a port, but at the same time it can’t quite match the image quality of the Windows version. Feature-for-feature there is parity, but the Mac version just isn’t as sharp as the Windows version.

Performance isn’t any better. Portal is an easy game to run and so we’re largely being academic here, but the “tax” for Mac OS X is roughly a generation in hardware performance. For the performance we’re seeing on a GTX 285 under Mac OS X the results are similar to what we’d see under Windows with something like a 9800GTX. Given that at the high-end the Mac platform is also a generation behind in hardware, and you’re looking at 2008 performance for Portal even with the best hardware you can get today for a Mac.

Ultimately having the Source engine ported to Mac OS X is going to remove the technical need to use Bootcamp to run Windows for games, but based on Portal it doesn’t remove the need to boot Windows for performance reasons. For long-time Mac users none of this should be surprising, but it means that we shouldn’t expect the Mac OS X version of the Source engine to be revolutionary.

Update: 5/15/2010

On Thursday after we published our article Valve pushed out an update for Portal that focused on fixes for the Mac version. The big fix was the following:

Fixed screen "fuzziness" caused by color correction operation



This fixed the blurriness issue we saw with the initial version of Portal. Texture and geometry quality is now as sharp as it is under Windows. Performance remains unchanged, while there is still an image quality difference between the two due to lighting differences and a general degree of fogginess that still appears on the Mac OS X version.

Portal - Windows. Click to enlarge

Portal - Mac OS X w/Patch. Click to enlarge.



View All Comments

  • botrytis - Thursday, May 13, 2010 - link

    What is it saying is that Apple is not giving their users the best of the best. I have a Radeon 5770 1 GB in my system (~150.00 dollars for a PC clone - which is mid-level) that would do better than the GTX 285. Any other cards on the MAC system would be slower that that and may get to unplayable.

    This game is very easy in the system to as far as resources, so the graphic intense might as well NOT be ported to the MAC until Apple decides to improve their system for gaming.
  • Penti - Thursday, May 13, 2010 - link

    It won't be unplayable god damn it, stop that bullshit. This is benchmarks with 2560x1600 with 4xAA/16xAF. With drivers 54% slower (at max res) then the Windows version, a HD4870 will be faster if it's drivers are more to par on with the Windows driver performance. iMac users might turn off MSAA and AF and run fine on their 27" iMacs with high details. They are not going create a game that won't run on Macs. The god damn point of the article isn't to disprove OS X / Macs as a gaming platform. The Mac system requirements are just X1600, 8600M or up. I.e. any mac with discrete graphics. (Counting out 7300GT though.). Just stop your nonsense. Reply
  • cknobman - Thursday, May 13, 2010 - link


    Simma down buddy. Pills are good, pills are goooooooood.

    Take your meds, get our your ipad, and go back to chilling watching webcasts of reverend Jobs and his faithful teachings.
  • danielromero - Thursday, May 13, 2010 - link

    Louis: Pipipipipipipipipills here!

    You should have done it Left4Dead style.
  • SoCalBoomer - Thursday, May 13, 2010 - link

    That wasn't the point. . . the point is that the game tends to run HALF the speed and with lower image quality than on an equivalent Windows machine - BECAUSE Apple is behind on their hardware and their drivers.

    And while Windows users could blame poor performance, previously, on the manufacturers' sucky drivers, Apple owners have only Apple to blame. Microsoft made DirectX specifically for gaming while Apple relies on OpenGL and is behind the curve on that too . . .

    You only hate it when the comparison is Apples to "apples".
  • Penti - Thursday, May 13, 2010 - link

    cknobman, SoCalBoomer etc

    Sorry I'm not a Apple user, but he had already came with this bullshit already in another comment. It's simply not as HE describes it. I know the point is not that, but I was just reacting to the point he tried to push several times.

    More to the point to the post I'm replying to here, Apple doesn't have the full responsibility it's mostly nVidia and ATI that has that, it's always up to the graphics vendors to implement OGL and they aren't dependent on whatever Apple does, the framework makes it fully possible to implement the newest features and any extensions they want and the performance is all in the graphics vendors hands, they can even release drivers on their own and do occasionally. Of course Apple makes a point to include the drivers just as any OEM would and the platform itself has drawbacks but consoles for example are way behind even Apple in this front at this point in time. It's not Apple that develops the drivers. But of course the platform doesn't encourage monthly drivers updates. Apple have embraced Open GL and Open CL and is definitively not just lagging behind. Apple is an OEM and many of them are as bad with regards to hardware. IQ and speed is a combination of Valve, nVidia and Apple, it's only behind Windows performance because of nVidia. But as this is a new port/engine which uses different infrastructure it's not a comparison between the gameability of the platforms or performance in general. I know very well that the drivers themselves are of less quality especially when it comes to speed. And that Apple won't put as big effort into gaming. That's not what I was reacting to. It's not Apple that wrote the game engine, and I don't think Valve failed here either.

    botrytis views was fully unsubstantiated FUD. I know Portal works good on the macs out there like the new 15" MBP with 330M. So it fully fills it's purpose. No need to spread more nonsense like he did. Open GL is designed for gaming PS3 does fine with about the equal features of OGL 2.0. A game like Portal don't need the latest OGL 3.2 features or DX11.

    Valves customer base aren't Mac Pro users with after market GTX 285's. Point of the article is of curse different from botrytis point, but I wasn't replying to the article there.
  • AssBall - Thursday, May 13, 2010 - link

    Mac Gamer???

    Pardon me, but WTF is that?
  • gaspard - Friday, May 14, 2010 - link

    I suggest the article could have used a few mid to high level macs, which would have provided a much better picture of the performance, as a hackintosh with a GTX 285 is not really a good example..

    Case in point: according to my personal experience, and many members in the steam forums, ATI performance is not on par with NVidia performance in levels with water (green sludge?)
    For example: http://forums.steampowered.com/forums/showthread.p...

    Also the colour correction option reduces performance considerably.
    Currently (as at 2010-05-13) the latest patch for Portal has broken the transparent portals, unless you start the game in windowed mode.

    I've just tested Portal on my Win 7 machine and discovered that the VSYNC option uses triple buffering, whereas on the mac it's only double buffered or page-flipped, so frame rates between 30 and 60 are locked to 30 FPS on the mac...

    so to summarize, Anandtech, please test using typical mac gaming machines, such at the iMac, and maybe a MacBook Pro... etc
    I tested Portal on the iMac (Late 2009, 3.06Ghz C2D E7600, ATI Radeon HD 4670 GPU)
    I could get a nice 60FPS all the time, but had to run at 1280x720 with no AA and colour correction off, so performance is quite bad... It can be played at 1920x1080 but is very sluggish, unless you basically turn almost everything off...
  • hallstein - Thursday, May 13, 2010 - link

    Portal is currently giving some mac users a white screen of death, but happily in the fraction of a second of gameplay I am able to snatch before that, the framerate looks playable.
    (Problem exhibiting here on a Core Duo MBP w/ ATI x1600.)
  • t0njohn - Thursday, May 13, 2010 - link

    This is a known issue:

    Some users have reported disabling color correction or setting "mat_bloomscale 0"

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