Need help guys, got a bunch of 4x leftovers and don't want to undermind the potential of my burner Thank you.

4x @ 8x = coaster.

well it depends on the media and the type of burner. some 2x media burn fine at 4x (on certain burners). i haven't heard of any 4x that burn fine at 8x, but i don't watch it that closely. your best bet is to check cdfreaks.com.

I have tried 2x media on 4x burner and was creating coasters. I wouldn't recommend going over what the media suggest unless you are planning on a nice collection of coasters.

I believe that n99nyrwg is correct here. For example, I'm aware that the Plextor 708A can burn certain 4x DVD+R media at 8x while the NEC ND-2500A can burn certain 4x DVD±R at 8x.

that's close, i'd like to ammend that recommendation though:

I wouldn't recommend going over what the media suggest unless you know what you are doing

don't guess and check....that's not smart. you have to do research on the disc and it's history

I have a TDK 840G burner a.k.a rebadged Plextor 708A. I have burnt the TDK 4X media at 8X without any problems. No coasters yet. I think it depends on the media. All my media were RICOHs.

On some players, the video started skipping near the end of the movie. I think that it may be due to higher speed of burning. So I am now burning 4X + media at 4X and 2X - media at 2X only.

So if you are considering burning at 8X, try one disk first and make sure that it is not skipping near the end of the movie (I think it is the outer radius part).

it depends on the media and the burner

See, the thing is that any burner could burn 1X media at 8X speeds, but there's something called the error rate that comes in the way. At too high error rates, the media becomes unreadable fully or partially ("coasters"). I wouldn't recommend using 4X media at 8X even if it works, because there would be a much higher error rate on the disc, and if the disc gets scratched, smudged in the future, error recovery would be tougher for a drive (compared to a normal disc).

Of course, once DVD-media reaches the current CD-R FAR state, where, say 32X, 40X and 48X media are the very same discs, the story is different. Check on the disc ID's (there are tools that can do that, I forget the name), and check out Google; lots of sites have disc/drive/speed compatibility tables based upon info submitted by people like you.