About all those 7z files on PSX ISO section....

I just happen to try PSX ISO recently, and it mounted the img & bin file quite well, however it can't seem to read/run these "7z" files dl-ed from here though, what the deal with these files anyway?, are they not the same with img/bin?

No they're compressed archives like zip and rar files, you'll need either 7zip or winrar to open the files.

Winrar will open them fine, just extract them like you would any other compressed file.

Problem is, even If I can extract/open them, my PSX emulator couldn't read/run the file, is there any way to convert them to .bin or .img somehow?

no, 7zip is an archive, the .iso/.img/.bin files are inside the 7zip. You must extract the files and the extracted files are readable by ePSXe

Ah..., how silly of me, misinterpreted what you guys mean until a moments ago, thanks for the clarification, now my only problem left is only the yet unreadable .nrg file until I figure it out.

check your other thread.