XPS M140 with Intel 915GM Chipset isn't displaying 1600x900

Hello! So I have this great old XPS M140 with the infamous 915GM chipset that is refusing to display 1600x900 on my external monitor (which I just got). I've attempted toying with all the Intel settings with no luck. I've also made it show resolutions that the monitor cannot apparently display. I'm pretty sure it's possible because the level right below it is 1400x1050 then the one right above it is 1600x1200. I've been crawling the web for over eight hours now with no results, so any help is greatly appreciated! Thanks ahead of time!