iMac 21.5″ i3-3.2Ghz with the Radeon 5670 (Mid-2010) in gaming

If you hate 27″ screens and wanted to get the strongest video card Apple offers in the 21.5″ model, this is probably the machine you went for (or… the machine you’re thinking of getting).

In any case, the Radeon HD 5670 offered in the iMac is actually an ATI Mobility 5730m. Higher model number, but mobile chips are clocked a little lower, so you’ve got roughly the power of a desktop 5670. If you’re wondering why Apple goes with mobility GPU’s, they’ve got pretty good reasons:

  • Mobility chips use a lot less power. It’s tough to find a desktop machine that competes with the iMac’s power consumption. This makes the tree-huggers happy, as well as the people with high electric bills. Incidentally, it also means Apple can go a little less crazy on the power supply in the iMac. Everybody wins.
  • Mobility chips generate less heat. Related to the power thing above. Less heat means the fans don’t need to sound like jet engines. Apple doesn’t have to worry about people burning their hands on the aluminum. Your air-conditioning doesn’t have to work as hard in the summer. Good plusses here.
  • Mobility chips tend to go on small circuit boards. Since these are the things you find in laptops, they’re smaller. There’s a lot packed into the guts of an iMac so this helps immensely.

Moving on, because this is a mid-range card and I’m used to high-end cards, I was curious to see how this would fare in games. I ran it through World of Warcraft (on the Mac side), and through Dragon Age: Origins and Mass Effect 2 in Windows through BootCamp.

Here are the results:

You’ll notice 2 resolutions were used, adjusting the Quality Slider in WoW for different test points. This was done in Dalaran in the wee hours of the morning (few people on) in a location where the frame rates were typically low. Framerates differ massively throughout Dalaran, and I wanted consistent numbers that weren’t very optimistic.

To give a playability perspective, I hopped into a battleground (Alterac Valley), so that I could see if things felt smooth with 40 players.

The “Good” quality setting in AV was absolutely perfect. “High” was very strong too, although there were a couple moments where it wasn’t 100% smooth (but only for a moment). I’d recommend starting off at “Good” quality, and going to High/Ultra if you really feel you’re missing out. You can always back down again if you find things get spiky at inopportunte times.

In terms of Windowed mode, the game isn’t handled quite as well (even though the FPS dictates it’s about the same). Spinning in circles, it’s not 100% smooth all the time. It’s still perfectly playable, and many people probably won’t even notice the minor spikes (which look like a single dropped frame).

Regardless, in the case of WoW, I’d recommend playing at full screen, full resolution, and medium to high settings. It looks great. Use VSync though, or you will get tearing during the times/locations when the framerate skyrockets above 100fps.

Next up is Dragon Age: Origins (bootcamp/windows 7). You’ll notice a couple things:

  1. It scales pretty evenly as you lower the resolution.
  2. The runs where Frame Buffer Effects was enabled (the top section) are a fair bit lower in framerate.

I’ll start by saying that all these resolutions felt playable. However, I have very strong recommendations (and I’ll explain why for each):

  • Set Graphics Detail to Low. The reason is that low is bright, and Medium/High/VeryHigh are dark. The higher settings make everything look dark, and in particular, shadowed areas look way too dark. The higher settings also takes away from the crisp-ness. It makes things look smooth, but not in a good way. Use low. The pros in terms of looks outweigh the cons. As a side benefit, you get slightly better FPS.
  • Set Frame Buffer Effects to Off. There’s a scene in the Post Coronation where sunlight comes through the window. Frame Buffer Effects actually make the sunlight look really good. So why turn it off? Because everything else looks so white it’s washed out. Faces look white and bland. Bright items are just too bright. The effects seem to be applied to *everything* which more often than not is a bad thing. These effects also suck up a lot of video-card juice. Turn it off.
  • Set Texture Detail to High. It costs you about 2fps at most (closer to 1 and a half), and you get improved quality out of it.
  • Anti-Aliasing doesn’t seem to make much of a difference visually. It might at a lower resolution, but at the default, the couple things that were slightly jaggy before AA was turned on were still jaggy after. It’s possible that it has more of an effect during conversations (where you have a close-up view), but I’d be inclined to leave it off unless you’re YouTubing one of the chats or something and want to give it a try.
  • Use VSync. Less tearing is good (and it doesn’t seem to hamper performance just by being on)

A couple critical notes if you decide not to listen to me, and are determined to use Frame Buffer Effects anyway:

  • Frame Buffer Effects + Full Screen Mode + VSync = 30FPS max. Try that combination, and you’ll be limited to 30FPS. You either have to turn off VSync or use Windowed mode. Don’t ask me how or why I managed to find that deadly combination.
  • Frame Buffer Effects + Low Graphics Detail = blindingly white. If you use Frame Buffer Effects, you’ll want to use Medium/High/VeryHigh.

And finally, if you choose to go with Medium/High/VeryHigh for Graphics Detail (which makes everything quite dark), you can try enabling Frame Buffer Effects so you can see a little better. Again, you’re better off choosing Low and keeping Frame Buffer Effects off.

TLDR version: Use Low/0xAA/High/Off, turn on VSync, and the game will both look and feel great at max resolution (and play just fine in a lower resolution mode if you’re looking to play in windowed).

Finally, we have Mass Effect 2 (bootcamp/Windows 7). During the opening scene (when you walk through the firey ship to save your friend), I actually experienced some really odd behavior. Every resolution from 1920×1080 down to 1280×1024 seemed to hug the 30FPS mark. Dropping 1 more spot to 1280×768 however instantly started hugging the 60FPS mark. It’s not a big deal (it’s a minor scene), and I’m not sure why it was like this, but it’s an oddity I thought I’d mention.

In any case, once you’ve started playing the game (right after you wake up), you’ll see fairly typical frame rates, with steady FPS improvements as you lower the resolution. ME2 actually looks good in full screen regardless of the resolution you pick, so if you find the framerates aren’t quite what you like, lower the resolution some.

During my testing, the mouse seemed very quick/inaccurate at the higher resolutions (which made the gameplay feel choppy), but this can probably be remedied by changing the mouse settings. Chances are that I’ll play at a lower resolution though for better framerates, since the game doesn’t seem to suffer visually from non-native resolutions.

One thing to note is that the video options (High Quality Bloom, Dynamic Shadows, Light Environment Shadows, Film Grain) don’t seem to have any discernable impact on the frame rates. Like WoW, the frame rates seem to flutter (although not as drastically), so it’s hard to tell for certain, but I suspect that you’re looking at a difference of perhaps 1-2 FPS.


The 21.5″ iMac with the i3-550 and ATI Radeon HD 5670 (5730m) seems to perform pretty well overall in games. You’re not going to be cranking everything to maximum, but you certainly won’t be stuck playing games at the minimum settings. Games will generally look good, and play well.

Certainly, you can put together a custom PC  that outperforms the iMac for less, but then you lose out on OSX (when you’re not gaming), and a few of the minor niceties like the low power consumption and simple all-in-one design.

One flaw that does present itself however is the Bluetooth “Apple Magic Mouse”. It’s magic in that it magically stops working at every opportunity in Windows. It continually isn’t recognized when booting Windows, and when waking from Windows sleep. If you plan to grab this iMac an install Windows through BootCamp, invest in a mouse too (and make sure you have another USB keyboard around that you can use for the actual Windows BootCamp install). Maybe in the future, Apple will fix the BootCamp software. Then again, it’s possible they’re trying to punish Microsoft for making terrible Mac Apps by making a faulty Windows one.