I have my PS3 connected to my 1080p TV via HDMI. I have all the settings set to 1080p and HDMI. My problem is this:
The only game I have right now is Assassin's Creed, which on the back of the box says it can be viewed in 720p or 1080i, yet it automatically displays in 720p and I cant find a way to make it 1080i... I checked the PS3 site and User Guides but couldnt find anything... Anyone know how to do it?
If you really want it in 1080i, go into the Video settings in the XMB, and UNcheck 720. It will scale to 1080, and likely won't look as good. Also, other 720 games that DON'T support 1080 upconversion will now be down-scaled to 420p.
Bottom line? Keep everything checked, and let your games run at their native resolution.
As everyone suggests, it's just better to leave all of the supported resolutions in Display Settings checked. I tried the upscaling trick with Drake's Fortune just to see what the game would like at 1080p and I couldn't see any difference whatsoever. Then I forgot to change the setting back and experienced the unfortunate side effect of unchecking 720p when I played the Battlefield demo and noticed that the game looked like ass now that the resolution was now downrezed to 480p.
I don't know why Sony decided not to support scaling like the 360 does as there are plenty of HDTVs out there that only support certain HD resolutions and not others.