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

  • robco - Monday, May 17, 2010 - link

    Not pulling any numbers out of my ass. Check the battery tests in the Mac section of this site and you'll see you can get Apple's stated numbers easily. I rarely use the optical drive and keep the display brightness around 1/3 as well as the keyboard backlight. Other than that, I can work for five hours easily, longer if I switch over to the 9400M.

    Now if you're doing something like gaming, the battery won't last that long. But for basic productivity tasks, I can get those numbers easily. In any case, the MBP has excellent battery life compared to most other laptops in its class. And back to my original point, there are many reasons, at least when it comes to laptops, to choose a Mac.
  • KoolAidMan1 - Sunday, May 16, 2010 - link

    Both of you are wrong, NONE of the Macs have had Intel graphics for the last two years. This is why the new 13" MBPs use faster Core 2 Duos instead of i3 or i5 CPUs, because it was the only way to get an integrated GPU that didn't suck. It was either use the crummy IGP on an i3 or i5 Arrandales or use a faster C2D with an nvidia 320GT. Discreet GPUs like you'd get in a 15" or 17" Macbook Pros wasn't an option simply because space is so limited inside that little 13" enclosure.

    Given how much the OS X desktop leans on the GPU, it was an obvious choice not to downgrade from the prior 9400M to Intel graphics.
  • Scali - Monday, May 17, 2010 - link

    The i3/i5 GPUs aren't all that bad.
    They can keep up with the AMD IGPs quite well, and in some cases even outperform the nVidia ones:
  • hsew - Saturday, May 15, 2010 - link

    Hackintoshes, at least from my experience, do not run as fast as a mac, period. This is due to the fact that several key files are altered/added in the hackintosh OS.

    Even if you do not agree with that, I think the test should be redone using an actual macbook...
  • KoolAidMan1 - Sunday, May 16, 2010 - link

    Finally got around to installing Portal on my iMac, i7 860 CPU and ATI 4850 GPU, a slower machine than my home built Windows 7 PC with i7 860 CPU and GTX 285 GPU outputting to a 24" LCD.

    Gotta say, running Portal on my iMac at native 2560x1440 with AA off, I am super happy with its performance and the way everything looks. I got a consistent 60-75fps with vsync off, with occasional dips to the mid-40s if I was doing some crazy portal viewing. With vsync on it was pinned at 60fps for pretty much the whole time in the maps I looked at.

    It performed way better than I expected, given the 4850 that has to push so many pixels. I was ready to drop down to 1920x1080 but I didn't need to. It looks awesome at such a high resolution and on such a gorgeous display, people with higher end iMacs (I can't imagine the 4670 in the baseline iMac doing so well) and pretty much any Macbook Pro will be very happy.

    I did not compare Windows performance since I don't have it installed on my iMac, and I did not compare anything on my 2008 Macbook Pro since I nuked Win7 on that machine last week (awesome timing to sell it; I'd totally have kept and benchmarked it had I known Steam was dropping this week). I'd love to see the site run benchmarks on actual iMacs and MBPs instead of hackintoshes, hopefully soon!
  • smartalco - Sunday, May 16, 2010 - link

    Maybe this wouldn't make that big of a difference to performance (although I've always been under the impression that AA causes a huge performance hit), but is it possible that some of the performance hit is because the AA is so much different between the Win and OS X versions? Specifically, to my eye, the OS X version looks like it has nearly double the AA applied, I've linked to an image that shows some of the more obvious areas blown up to double the size so you can see for yourself. Could you possibly run through all the AA options on both platforms, and see if the comparable modes are actually different between versions? (ie: find if 8x AA on Win looks closer to 4x AA on OS X?)

  • GTVic - Sunday, May 16, 2010 - link

    Quote: "This fixed the blurriness issue ... Texture and geometry quality is now as sharp as it is under Windows ... there is still an image quality difference ... due to ... a general degree of fogginess"

    That does not make much sense, apparently they fixed the blurriness so it is just as sharp as a PC but it is still foggy. Huh?

    The one thing that is obvious is that the Mac version does not support HDR as you can see all the intensely bright areas are at normal illumination on the Mac.
  • afkrotch - Monday, May 17, 2010 - link

    My friend tried this on his Macbook. The model before they came out with the solid aluminium design with non-user replaceable battery. He says the game plays, but he can't see into the portal. Reply
  • star-affinity - Monday, May 17, 2010 - link

    That ”portal being black” issue should be fixed in the latest update.
    Relaunch Steam and it should automatically download it.
  • Ninjahedge - Monday, May 17, 2010 - link

    Um, I would like to say "amazing" but this isn't. Just a few posts into this thing and everyone is going on an AppleTirade/Windows War.

    This is about the port of the game, not the cost of an Apple, or teh commercials, or computer science majors, or Linux....

    The only thing that seems to come through here is that Apple machines are limited because they were not developed with gaming in mind. Ironic when they had the best games back when I was gong through college (Fools Quest and Sim Earth? TETRIS??!?!?). They seemed to have realized that they could not compete with the latest and greatest while still maintaining hardware control and compatibility, so they dropped the gaming engines and concentrated more on visual presentation and linear OS management.

    And it worked. Even with their small market share, they are able to charge much more for their product, to HAPPY CONSUMERS, than any other company. SONY and M$ are jealous of that and wish they could do the same, but they have not been able to squiggle their way in (or back in as is the case with SONY) the semi-literarte ArTechs out there that feel intimidated with setups and other procedures.

    Back to topic, what does this do? It makes them slower on games. Is that a killer? No, but suffice to say it is not a selling point either. Apple simply needs to opsn up a bit more if they want to succeed here, but in doing so it will make it hard to keep control of their hardware lock that earns them their money now.

    Bottom line? Install windows on the Mac to play games, or just get a 2 year old machine that will play it better for 1/4 the cost!!!! ;)

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