Your Optiplex will probably run 16GB.

Probably. Dell’s official specs are conservative. The chipset usually supports 16GB even when Dell only certifies 8GB. That said, the proprietary BIOS can be picky about memory.

Here’s the catch: You need the right stick type. Look for 2Rx8 (dual-rank, x8 chips) or 1Rx8, 1.5V, non-ECC, unbuffered. Avoid 2Rx4 or anything with “low density” marketing that actually means higher density. Older Optiplex models (790, 7010, etc.) often max out at 8GB per slot with 4GB sticks – 2x8GB won’t work at all. Newer models (3020, 7040, etc.) usually take 16GB fine.

Quick test: Check a user forum for your exact model. If people run 16GB, grab two matching sticks from a brand you trust (Crucial, Kingston). Buy from somewhere with easy returns. Worst case, you’re out shipping.

Don’t let Dell’s spec sheet scare you