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I have a mid-2012 model MacBook Pro, with the following ports:

  • 1 ethernet
  • 1 FireWire 800
  • 1 Thunderbolt
  • 2 USB 3.0

(I have to use my Thunderbolt port for an external SSD, so that port is occupied.)

However, my CinemaHD monitor connects currently into the Thunderbolt port as well, with a DVI-d to Thunderbolt adapter.

I've been searching for awhile for a solution without any luck. Essentially, I need either a cheap Thunderbolt splitter (I don't think these exist...?) or a way to adapt my DVI-d male plugin to a female FireWire 800 or USB port (and have that allow my MBP to recognize my external display).

Any advice would be greatly appreciated. Thanks!

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The most graceful solution is to replace your single-port Thunderbolt SSD with a dual-port one. LaCie makes one.

Or replace your Cinema HD display with the Thuderbolt display.

FW and USB aren't graphics busses, so they're no replacement for graphics busses like DisplayPort (including Thunderbolt)/HDMI/DVI. An "adapter" from FW/USB to DVI-D would actually be an external graphics card / GPU.

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Thanks for the reply. This is for work, so I can't replace the LaCie external SSD they gave me (just one Thunderbolt port on it) or buy a new monitor. Are you saying something like this wouldn't work? Wouldn't that essentially allow me to plug my monitor into a USB port? – praguian Aug 8 '13 at 20:01
You do not want to plug your monitor into the USB port. The adapters work, but the speed is not fast enough for... well anything other than viewing spreadsheets. – Keltari Aug 8 '13 at 20:03
@Keltari So I really am out of luck for a cheap solution to this? – praguian Aug 8 '13 at 20:05
No, Spiff had a decent solution. Im editing his post to include a link. – Keltari Aug 8 '13 at 20:11
@praguian Well, if you're using that external display for video editing, you're probably not going to like the performance a typical USB-connected external graphics card is going to get you. I think I'll stick with my original Answer that you should either ask your company to swap out your external SSD for one with a pass-through Thunderbolt port, or ask them to swap out your display for an Apple Thunderbolt display (which has a pass-through port). – Spiff Aug 9 '13 at 0:53

LaCie themselves only claim 385 MByte/sec throughput on the SSD you have, regardless of whether it's over USB 3.0 or Thunderbolt. That's just over 3 gbits/sec, which is slower than USB 3.0's bus max of 5 gbits/sec, so it checks out.

So put your SSD on USB 3.0 where it will still be every bit as fast as it can be, and put your DisplayPort > DVI adaptor > Apple Cinema HD display on the Thunderbolt/DisplayPort port.

[I had put this suggestion as a comment on my other Answer, but with the addition of the LaCie throughput specification information, I think it's a valid yet different Answer on its own.]

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I see the LaCie dual-port HDD you linked boasts twice the transfer rate as my you know what drawbacks I'd have using that over an SSD? Are transfer rates the key point for video caching, or is there a read/write speed consideration I'm not seeing? Thanks again, I think this may have to be my solution for now if USB 3.0 will really match the transfer speeds I get through Thunderbolt w/ my LaCie. – praguian Aug 9 '13 at 14:16
@praguian I'm looking carefully at the technical specifications, and it seems clear that the HDD is not faster, it's a lot slower as you might expect. It's the SSD configs of that enclosure that are quite a bit faster, at least in one direction, than your other SSD. – Spiff Aug 9 '13 at 17:13
Thanks for looking into that. So I'd really have to get the $700 SSD version of that dual-port drive to accomplish both optimal read/write speeds for my video cache and daisy-chaining my Thunderbolt display. Alas. – praguian Aug 9 '13 at 17:31

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