Wordpres not runing under new dedicated server

I just moved my installed wordpress from shared hosting (which was working just fine) to dedicate server and I keep getting "500 Internal Server Error" error http://ift.tt/1Ql0CvZ . I tried deleting .htaccess, renaming plugins folder, increasing memory and nothing worked. What else should I try?

One thing I noticed is that when I change PHP support from "FastCGI 5.4.45" to "Apache 5.4.45" I get "504 Gateway Time-out" error.

Thanks!

via Chebli Mohamed