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

  • sxr7171 - Thursday, May 13, 2010 - link

    Right to the point. I guess this is just step1 for Macs and gaming. Reply
  • Zweben - Friday, May 14, 2010 - link

    The Mac screenshot is inaccurate. There's no way it's running in 2560x1600. I could tell right away, because, although it was unplayable, I tried Portal at the same res on my Mac and it looked completely different. So I went to the exact spot where the screenshots here were taken and made my own.

    The screenshot was taken with all the settings on the highest quality on a Mac Pro with an Nvidia 8800 GT. While the lighting is indeed duller on the Mac, the sharpness is the same as on the PC in my screenshot. Completely different than the Mac screenshot provided in the article.

    Here's the screenshot: http://bayimg.com/image/eamojaack.jpg

    Also, this site ought to have contact info up to send in corrections like this.
  • Ryan Smith - Friday, May 14, 2010 - link

    They have finished writing our About page yet, but I can be reached at ryan.smith@anandtech.com. The same goes for the rest of the staff members.

    Anyhow, I can certainly understand your skepticism, but the screenshots I uploaded are the originals. It was absolutely running at 2560x1600. Someone else posted that Valve pushed an update out today for Portal, and you may be seeing the effects of that update.
  • Zweben - Saturday, May 15, 2010 - link

    I don't doubt that the resolution was *set* to 2560x1600, I was just saying that it didn't look like it was *rendering* at 2560x1600. Changing the resolution setting in Portal doesn't change the monitor resolution, it just changes the resolution at which it's rendering, and stretches it to your display's res. Because of this, screenshots always match the display resolution. So even if the game wasn't rendering at the res it was supposed to be, it would output a 2560x1600 screenshot. Reply
  • khoonirobo - Friday, May 14, 2010 - link

    I refer all of you to


    I myself would identify as a Linux fanboy.
  • PaperTiger - Friday, May 14, 2010 - link

    And thats what they've done today. I've bought more games for my mac in the last 24 hours than I have in the last 24 months. And I'm having a pretty good time of it. I'm not much of a gamer, and when I do play games I usually play on my PS3 (which only cranks out 60fps IIRC) I honestly don't even know how to figure out my frame rate on a game, and really don't care. If the game plays smooth I don't think I could see the difference between 60fps and 200fps. But thats just me. If you can, you probably should use the computer that best fits your needs. I don't think you'll ever run into a Mac user that will say he bought his computer to game on. It's kinda like fat chicks and The Wii. Everyone knows they're inferior, but people love to play on them.

    BTW... OS X is Linux (Darwin Kernel + BSD + Aqua UI)

    Good night now!!!
  • killerclick - Friday, May 14, 2010 - link

    I don't ride fat chicks and neither should you. Same goes for the Wii Reply
  • 0roo0roo - Friday, May 14, 2010 - link

    Just wondering how actual macs perform.. Reply
  • star-affinity - Friday, May 14, 2010 - link

    I agree that the looks of Portal on the Mac is blurry compared to the Windows version. The funny thing I noticed is that on the ”main screen” (where one get when starting the game) all textures and edges look sharp, but once the game is launched things look a bit blurry, as if not running in native resolution even if one is. Anyway, I saw there was an update released, will see how it looks when I get home.

    Also the performance for Portal is *much* worse on the Mac version – you can feel it when playing the game and I have an i7 processor and an ATI 4890 graphics.

    What makes me wonder: if how Portal performs is only a matter of bad drivers, why are there other games that run well on Mac OS X?

    Call of Duty 4 for example.
    While a little different (less reflective on wet ground for example) overall It looks as good in Mac OS X as in Windows on my setup. The same goes for frame rate – I would say it runs just as well in Mac OS X as in WIndows.

    World of Warcraft is another example – according to my simple tests I even got a few frames per second *more* in Mac OS X compared to Windows.

    Torchlight is also released for Mac on Steam and that is sharp and smooth as silk in Mac OS X (on my setup).
    Is Torchlight a much less demanding game than Portal?

    How do you explain all this if how a game performs is *only* about Apple's OpenGL drivers?
  • ShandyPants - Friday, May 14, 2010 - link

    Disable color correction in the settings and the blurriness will disappear, this setting seems to be broken at the moment.

    Portal performs well on my i7 iMac, it's still VERY early days and I think they've got off to a good start.

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