Don't spend money on DDR3 RAM for that old OptiPlex.

Probably not worth it. An OptiPlex 7010 is from 2012—DDR3, possibly Ivy Bridge. Even if you find 2x8GB sticks for $20 on eBay, that’s $20 you could put toward a used Dell with DDR4 and a much faster CPU. The 7010 will still feel slow in 2025 because of the processor and old SATA storage (assuming it has an SSD). 8GB to 16GB helps if you’re hitting swap, but it won’t fix the bigger bottlenecks.

If you can get the RAM for free or nearly free, sure. But paying any real money? I’d skip it. That machine is past the point of cheap upgrades making a meaningful difference.

Save your cash for something that won’t feel like a time capsule.