Relative GPU performance on 21.5" and 27" iMacs?

If you're truly interested in GPU performance, you shouldn't be looking at the 6770m models

The 27" at native resolution has a lot more pixels to push around, and the 512MB 6770m chokes on it. By comparison, it merely struggles with the 1080p on the 21".

Depending on your intended use, either might be just fine anyway.

Edit: If you're waiting for an update, then the comparison isn't valid. A GTX 650M or 660M would perform pretty similarly at both resolutions.

 

I'm not a gamer, but can't you run games in a 21" size window on the 27" display? I don't mean changing screen resolution, but I remember games back when running in a smaller window in the center of a bigger display. If so, then you could have the added workspace of the 27" as well as the gaming speed of a smaller screen.

 

Finding benchmarks/reviews for 2560x1440 is very hard. Just about nobody but Apple runs mobile cards at that resolution.

If you're interested in the 2011's, here's how the 6770m would fare on the 21":
http://www.notebookcheck.net/AMD-Radeon-HD-6770M.43955.0.html. You could knock the 27" down to the same resolution for the same results; being a non-native resolution it's possible it might appear blurry to you. I can't find any numbers at all to show you for 1440p, but it'll probably feel 20-30% slower or choppier.

 

You can basically forget about running games at 2560x1440 with that card, so even on the 27" iMac, you would have to run at 1920x1080 or even lower to be honest.

 

I'm not much of a gamer, nor an expert so can only go with personal experience since getting my 21.5" 2011 iMac last week with the 6770M in.

Have played a few games on it under OS x. Handles them fine though not always at the highest details/resolution. Portal 2 with everything maxed out runs at 30fps and is absolutely playable, but thats portal 2....

Deus Ex HR took some tweaking but at 720p with most things on medium settings get a very decent frame rate and it looks good to me, but again I mainly game on xbox 360 so....

Serious Sam 3 medium settings and get a playable if not what (the pros would call playable) framerate of between 25 and 40 fps. Could turn things down lower if you demand 60fps.

However, I understand you can use bootcamp and under windows the performance is better in general.

For casual gaming like I do, then its fine. If you're wanting to play a large variety of games then bootcamp, if you're wanting the very top settings for the latest games then don't get the 6770m iMac....

Would be interested to here what the gaming performance is like under ML and whether the GPU drivers are improved for gaming in OS x.

 

You should get the 6970M with the 27" iMac, its around 2x faster than the 6770M...