XPS 8930, HDD temperature 50°C ?

I cannot find any Dell documentation that discusses temperature. Perhaps run the ePSA diagnostics, page 139.

No, the PSU fan simply pulls hot air out of the PSU. There are two system fans =
CPU fan
Chassis fan

The larger chassis fan should be enough to cool the system and all internal components. Under stress, you will hear the chassis fan ramp up, that is normal.

I changed my PSU from a smaller fan (Cooler Master V750) to a slightly larger fan (Corsair RM750i) -> with the hope that it takes out more hot air.  It reduced the temperature from 50 C to around 48 C (just internet browsing & checking emails).  Then I moved my primary hard drive from the primary hard drive bay to the 3rd hard drive bay (lower left in the photo). I thought that there would be more ventilation down there and it may be cooled by the airflow coming in from the back of the computer.  This changed the temperature (again just internet browsing & checking email) to around 45-46 C.  It will go up to about 48 C when installing programs or after a system restore.  But it will stay at around 45-46 C when watching YouTube videos.  If this is normal for a 6 TB Seagate BarraCuda Pro, then all is good.  They just seem a little high for a brand new hard drive so I was wondering if anyone else with a Seagate BarraCuda Pro also has similar temperatures so that I can stop worrying if I have a defective drive.

By the way, do you agree with where I put my primary hard drive?  I put it in the HDD3 bay.  In its regular location across from the PSU, space seems cramped and there'll likely be a lot of cables directly in front of it (possible hot cables).  That's why I moved it to the HDD3 bay.  More space and there's an opening to the outside at the back for more ventilation.  Is there a disadvantage to putting it there?

7200 RPM drives by definition run hot.  ST6000DM001

https://www.seagate.com/www-content/product-content/barracuda-fam/desktop-hdd/barracuda-7200-14/en-us/docs/desktop-hdd-ds1770-6-1507us.pdf

http://knowledge.seagate.com/articles/en_US/FAQ/193771en

60C is the max listed temp.

There is no disadvantage to moving the HDD there.

I know 60 C is the maximum temperature for my hard drive but I wasn't expecting it to get in the mid to high 40's during light use (internet browsing, checking emails).  If you look back at the diagram of the XPS 8930:

I now put a sound card in one of the slots located in between the 3rd hard drive bay and the video card.  The sound card is sitting almost right up against the hard drive cage (there's just a little space in between the two).  I'm wondering if that's a good thing or a bad thing.  For the bad, it might not give any space for ventilation for the hard drive.  For the good, it might be blocking heat from the CPU and video card from getting to the hard drive.  And it also creates a narrower channel of air flowing out the back.  Does anyone agree with leaving the sound card in the slot just beside the 3rd hard drive bay?  Or should it go in the slot beside the video card and thus give the hard drive more space?  

Or can anyone recommend a fan that would fit inside the XPS 8930 and cool any one of the three hard drive bays?  Any particular part someone can recommend?