You couldn't be more wrong in your analysis. This is problem with dead pixels, nothing to do with the bulb, or menu settings. You have a defective batch of sensors. I am very disappointed with the the 1610HD projector. Have had many projectors, and this one is junk! Very disappointed.
Same Problem here with my DELL 1610HD.
I am using the Projector not that often but the white dots are breeding like rabbits every time I use it.
I am going to fix it DIY like and would like to know, if someone know, which serial number of the DMD chip was bad and where to get it from.
Thanks and Regards
DELL 1610HD is use 1280-6038B DMD, it is old version. you can buy a newest version 1280-6438B(produce by 2016 or 2017). Price is about 210USD, other version like 1280-6138B 1280-6238 1280-6338B both old version.
Exchange it you need prepare a quality DMD thermal pad, clean fan, clean dust in projector.
Need any technial support or projector parts can ask me, I'm a repair man, I have a ebay store (lamp-book).