custom res: interlacing timing, performance, etc questions

[Eruditass]

so I made a bunch of intermediate hd resolutions on my htpc for desktop and game use and noticed that nvidia's automatic timing standard set all of the ones inbetween 720p and 1080p to interlaced 1080i timing standards.

is it worth it to edit each manually and set it to non-interlaced with 1080 active vertical lines?

I obviously can't notice anything on the desktop as everything is still, but i remember in the old days how bad interlaced looked, so i fear 1080i default settings and 540 active vertical lines it will not look as good with the vertical lines. I know it doesn't work exactly like it did back then, where it only filled in opposite lines. On first glance it looks like it kinda fades in the previous frame, which is actually pretty cool imo and not all that bad of a tradeoff.

On the other hand, my 9600GSO isn't quite up to the task at the higher resolutions on some games. Would telling the custom resolution to have only 540 active vertical lines actually make the GPU only render that many instead of the full vertical amount specified? Would 1080i be a lot easier on the GPU than 1080p? If so, I'd imagine that the performance be quite good, and not all that noticeably different on slower motion games.

If the GPU renders at full definition and then only sends 540 lines to the tv, then all is lost of course.

I have it set so the GPU does the flat panel scaling.

In summary:

1. how much better is interlacing today? clearly it is not the same as i remember, looks like there is some kind of blending between the two frames that almost looks like vertical AA.

2. GPU performance benefit with custom resolution interlaced timing? or is it only taken into account when scaling after drawing the screen and is completely worthless to NOT do 1080p timings for all my custom resolutions.


*wasn't sure whether to post this here or video cards*

 

[Eruditass]

thinking about it more, it seems logical that the gpu renders the screen in full, then the scaling is what takes only half the vertical pixels. if this wasn't true, then the AA-like effect would not occur, and i would see half the precision in the vertical pixels, and it would look like 1920x540 stretched vertically essentially, ie shit.

so interlacing is and still is only done in the lack of a good display OR the lack of bandwidth / components inbetween. seeing as to how i have a 1080p set and HDMI that transmits 1080p perfectly fine, it seems a complete waste to ever use 1080i timing on any resolution, and to always have the gpu scale up to 1080p and transmit all 1080 vertical pixels. except maybe to save power or something. i will have to say 1080i looks quite great on this samsung set the way it deinterlaces and would certainly choose it over 720p, even in fast paced games (i just tried it in TF2 as a scout). it looks nothing like the 1080i stuff i have seen on other sets. tv channels may be a different story.

this is on the assumption that (2) is false, and it is currently too far past my bedtime to do benchmarks to confirm as well as editing my 10 custom resolutions that were automatically set to use 1080i signals. am i right or wrong?