I have a SATA II 240gb SSD and a SATA III 120gb SSD and want to connect one of these to my iMac's USB 3.0 port and boot

High Sierra from it. Which drive will give me the best speed and performance? I know I can install both and do respective

speed tests but can someone save me the time and hassle with a definitive answer so I can go through the install set-up just

Please help.

I didn't find the right solution from the Internet.

References: https://www.techadvisor.co.uk/forum/...-imac-4659234/

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