I am running such a setup for almost a year now without any problems. The WD drive I initially tried to use was horrible (spun down after 3 seconds of idle time, which made it constantly spin down and up), but the Hitachi drive is excellent. You have to use UEFI to make this setup work, if I remember correctly. Otherwise you can't boot from the mSATA SDD.
I have to update my post, in case somebody is interested in this setup. I got heating issues since last summer, and after having recently upgraded from the HGST Travelstar Z5K1000 to a Samsung 840 EVO 1TB SDD, it got worse. So maybe the Samsung drive gets hotter than the HDD, but either way a 7mm drive might block the air flow in the laptop too much.
I'm using the computer on a cooling pad most of the time, and then everything is fine. But the constantly running fan does get annoying at some point.
To me it looks like Dell intended the E7440 to run with a 7mm drive, because the space is there. But then they recognized the heating issues and sell it only with a 5mm drive or an mSATA card...
There is no problem with that orange flat cable, it just sit's under the 7mm ssd
There is a problem with that orange cable. It makes the HDD wobble and not fit in the space, since the cable it bulging up instead of sitting flush. I am trying to fit a 2.5" HDD 7mm.
Is there is a smaller cable available for purchase that fits flush? Or can the cable be pulled out and trimmed? I am afraid to apply too much pressure on the bulging cable, as it may pinch it and damage it. It is not a problem right now as there is a mSATA SSD in a converter cradle, which has lots of open space for the cable to bulge in. But try putting a traditional SSD or HDD, and you will know what I am talking about.
I found your thread and have a question (tech handicapped here). In your conversation it appears that 7mm DDD is better than the SATA. I am purchasing the Latitude E7450 and wanted to be sure I bought the best part. Is this correct?