I'm having issues connecting my iMac to my external monitor (Samsung SyncMaster SA350). I bought a Mini DisplayPort -> HDMI cable on eBay recently. The monitor works fine when connected to my MacBook Pro (13" Mid 2010), but it doesn't get detected by my iMac (21.5" Mid 2011). I believe I have tried pretty much everything. Rebooting with/without cable plugged in, detect display button etc.
Both my Macs run the same OS (Lion 10.7.5) so it shouldn't be a software issue. After doing some research, I have found the main difference is that my MBP has Mini DisplayPort, where my iMac has Thunderbolt port.
It should also be noted that the Thunderbolt port of my iMac works, as the monitor was previously connected with MDP -> VGA cable. But I now want to use my monitor's VGA input for other purposes, so I need a way to connect the iMac using HDMI.
If that is the issue, can anyone explain why and what I might do to fix it? And what is the difference video output-wise between MDP and Thunderbolt? Any compatibility issues I should be aware of in the future?