Quote - dpi is irrelevant to render size btw, just multiply the X and Y size required by 300 to get the pixel dimensions to render to.  3000 x 3000 at 300dpi would work out at 900,000 x 900,000 pixels which would crash most render engines tbh.

10" x 8" at 300 dpi works out at 3000 x 2400 pixels

 

Interesting math. I set my images up to render in inches at about 16 x 20 or 11x17 at 300 dpi. When I turn that number to ppi it comes out to about 3000 x something depending on the other linear size. I do it at that size so I can get a bigger image to work with for better detail when I paint or do post work and then parce it down to smaller sizes as needed for printing smaller images or for offset reproduction.

I certainly don't try to render at 900,000 x 900,000 besides Poser has a cut-off size doesn't it at 3200 or 3400...something like that. The render window almost always reads at FULL size 3000 x 3000 most of the time depending on linear size set up. Lately I saved the default render setup stage as a square format 3000 x 3000 to give me something better to crop from. For quicker renders to look see I render at either 1/2 or 1/4 quarter size to get an idea what needs to be fixed for final render so how are you getting the 900,000 x 900,000 size?