Hi everyone, i have no idea about Apple products, so i need a bit of help here if i may.

My son has the following late 2013 iMac, and has recently returned from a 3 week trip to Japan, and he has some 4k video from his GoPro, as well as a bunch of 1080p video from his Sony A7S camera, and he claims that when he is trying to watch the 4k video from his GoPro it won't play properly, and is very laggy, and he also claims that he is not able to edit the 4k video very well either.

iMac "Core i5" 2.7 21.5-Inch (Late 2013) Specs (Late 2013, ME086LL/A, iMac14,1, A1418, 2638) @ EveryMac.com

I have a lot of 4k videos in MP4, MOV, ProRes and XAVC-S formats and my Dell 2330 All in One editing pc with the intel 3770s cpu and HD4000 graphics will play them perfectly fine using Media Player Classic home cinema, yet his iMac has Iris Pro 5200 graphics and he says they wont play properly, but i have no idea what media player he uses.

I can also edit those 4k videos using my Video ReDo Professional editing software, but it does get a bit laggy on my timeline when i am trying to do my cuts, encoding is no problem tho.

Surely his iMac should be able to play 4k easily, and edit 4k video as well, or is it time to get himself something more powerful.

He would like to get a new 27" 5k model with the big 6700k cpu and an SSD, and have a 3tb portable Hdd plugged in with all his files stored on them, but it will cost him over $4,000 and he simply can't afford it yet after his trip.

Even the top spec 21.5" model will cost over $3000, which he said he will be happy with size wise.

Also, his current iMac only has the built in Iris Pro 5200 graphics with no dedicated card, the new 27" models have dedicated AMD graphics chips, but the 6700k cpu also has HD530 graphics built into it as well.

Can someone suggest something for him that will allow him to play and edit 4k video without too much trouble.

Cheers