Incase anyone ever needs the answer…I have a 27” 2010 iMac working in Target Display Mode with a M1 MacBook Pro using a miniDP to USB C adaptor that's capable of 4k60Hz.
Apple iMac 27 inch Desktop - MC784LL/A (2010) for sale online | eBay
3d apple imac 27 2010
Apple iMac 27" Mid 2010 Core i5 2.8GHz 16GB RAM 1TB HDD Radeon HD 5750 CHIPPED | eBay
apple-history.com / iMac (Mid 2010)
Apple iMac 3.6Ghz i5 27-Inch (Mid-2010) – MSU Surplus Store
Identify your iMac model - Apple Support
Sold - 21.5" iMac Mid 2010 // $295 - Boulder Mac Repair
Apple iMac 3.6Ghz i5-680 27-Inch (Mid-2010) *NO HDD/RAM* – MSU Surplus Store
Apple iMac 27-inch (Core i5) Review | Digital Trends
Identify your iMac model - Apple Support
Installing additional SSD in Mid-2010 27" iMac
server Festival marking imac 2010 Secure seven tolerance
Apple iMac 27-inch MC511LL/A (MID 2010). Core i5 @ 2.80GHz. 16GB RAM. 1TB HDD. High Sierra 10.13. for Sale in San Diego, CA - OfferUp
iMac 27-inch (Mid-2010) Core i5 2.80GHz - HDD 1 TB - 8GB | Back Market
Apple iMac 27-inch Core i3 3.2GHz Mid-2010 (MC510LL/A)
Amazon.com: OWC 2.0TB HDD Upgrade Kit Compatible With 2009-2010 iMacs, Includes: Thermal Sensor, Tools, 2.0TB Hard Drive : Electronics
27” Mid 2010 iMac Disassembled
