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

  • ahkey - Thursday, May 13, 2010 - link

    To all the Apple fanatics who've dropped 3-4 times as much on a "superior" system for half the games performance:

    How do you like *them* apples?

    Now I'm sure that performance will improve over time with optimizations, but it's great having such a simple chart to kill that smug sneer, even if just for a few seconds..
  • LaughingTarget - Thursday, May 13, 2010 - link

    That would never happen. It's part of the Apple EULA. Users are required to be smug about their inanimate objects, to project a culture around their inanimate objects, or Apple will disable your products. Reply
  • deanx0r - Thursday, May 13, 2010 - link

    Is there a reason why you have to act so arrogantly? I never understood the hate PC users have towards Macs. Getting into Mac isn't just about performance or bang for the buck. What you are buying with a Mac is the experience, something most Mac detractors fail to see. Reply
  • Sahrin - Thursday, May 13, 2010 - link

    Yes, and according to Apple part of that experience is 'great performance.' Obviously not the case.

    What I like is that Ryan tries to make it sound like the quality of the port is the fault of Valve - with no mention whatsoever about the quality of the platform provided by Apple (vis a vi OGL).

    Maybe you missed the "I'm a Mac" ads that were widely hailed by Apple and Apple Zealots. They presented falsehoods to the global community, which were largely (as I noted) accepted by the mainstream press and lauded by Apple fans. This is where the 'hate' (I would say 'frustration' comes from).

    More broadly, the frustration comes from the complete inability of any Apple user ever to present a cohesive argument as to why a platform that costs as much as 3x more than a PC is genuinely superior. On top of that, the company and its supporters (because they are certainly not customers) take a patronizing attitude ("gentlemen, start your copiers" or suing HTC) to anyone who dares produce something superior.

    As someone who has a healthy respect for the truth, I find Apple to be a cancer in society. Not because of their products - companies that overcharge for their products are a dime a dozen. It's the falehood they perpetrate (and is swallowed whole). Perhaps it's no conincidence that the only market they thave significant position in is America - a country that is so often mocked for its intellectual ineptitude.
  • Kaihekoa - Thursday, May 13, 2010 - link

    This is a wonderfully eloquent summation of many consumers' dislike towards Apple. Bravo! Reply
  • deanx0r - Thursday, May 13, 2010 - link

    I have seen the Mac and Microsoft ads. Do you really think they are representative of the community? How gullible you must be if you were so easily trolled by some commercials. Apple marketing was probably even more successful with Microsoft responding to their ads. For what is worth, I am mostly a Windows guy, but I know many Mac owners and have to work with them on a daily basis, and none of them has ever given me some condescending attitude about it. If anything, I see a reverse trend with many PC users looking down on Mac users, and the response to this articles is the eloquent proof of that.

    I am not saying there aren't any bad apples in either camps, but some of you guys are really quick at generalizing and putting up labels.
  • afkrotch - Thursday, May 13, 2010 - link

    I always love when PCs vs Mac arguements always turn for the worst for a Mac user. Cause every single arguement on the web about such, will turn into "it's for the experience" or "it's for the UI." Never anything that is quantifiable. Reply
  • deanx0r - Thursday, May 13, 2010 - link

    It's almost laughable to see Mac detractors react so vitriolically over such petty issue that is hardware preferences. I have yet to see a Mac user being smug about it, in contrast many Windows users are sulking over this issue as if they were to justify their purchase decision. Reply
  • windywoo - Sunday, May 16, 2010 - link

    I have seen many many smug as fuck Mac users. Reply
  • terath - Friday, May 14, 2010 - link

    The reasons why many prefer Macs have no doubt been outlined to you numerous times in the past and you choose to ignore them. But despite that, I'll post them *yet again*.

    First thing, lets get this myth of 3x more expensive out of the conversation. It's been debunked many times. At release, Mac hardware is pretty on par with other brand name hardware such as Sony or Lenovo. The value decreases afterwards. It is never as bad as 3x. It is never even 2x.

    Second, it is the experience yes, and system design. No other computer is as well integrated as a Mac. Perhaps Windows 7 can come close now, but as a package, Macs are very nice. Sadly, their towers are overkill for the majority of people and priced accordingly.

    Third, Macs have nearly taken over computer science. Why? Because Mac OS is a unix. And computer science work revolves around unix. This is because the tools are well suited to the job. No, the command line is not user friendly in the least.

    Performance wise, there is not a huge difference, at least for serious computations. The differences in portal could be due to numerous things: perhaps the hackintosh drivers are not optimized (highly likely), perhaps OpenGL is just not as good as DirectX, perhaps the port isn't optimized yet. It's a game, it'd be nice if it was on par, but people don't buy macs for games. They buy them for work or an easy home computing experience.

    As for getting all upset over software and hardware, you really need to get over it. Most people just want to get things done and no doubt find the zealous ignorance portrayed by "OS fans" hilarious.

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