Macbook Pro Guru's - Advice Needed

[MarcB]

So I currently have a MacBook Pro Late 2011 i5 2.4GHz with a 512GB SSD and 16GB of RAM running macOS High Sierra 10.13.6

Due to the age of the MacBook I now can no longer update any software and I cant get Mac OS Catalina 10.15.3 , The MacBook also has some issues where the fan is kicking in all the time and its down to a broken cable in my screen going to my camera as there is a temp sensor there, To get this fixed I would need a new cable and the time that would involve to do this is not cost effective.
The head phone jack also does not work and to get this working I would need to change the logic board and that would cost over £100 alone for the part.

What I have done is rather than throw £200+ at a MacBook that cant update I have went and bought a Mid 2012 MacBook.

The MacBook I have bought is a much better spec.
Mid 2012
MacBook Pro 13"
2.9GHz Core i7
16GB Ram
256 SSD + 750 HDD (750HDD in CD/DVD Drive)
Mac OS Catalina 10.15.3 (Up To Date Software)

Now the 2011 MacBook is almost identical to the Mid 2012 and I know that the Hard drive and the RAM can be swapped and changed no problem but what I want to know is the following.

Can I remove the 750GB HDD from the CD/DVD drive and replace it with the 256GB SSD and then take my 512GB SSD from my 2011 and put it in the Mid 2012

Mid 2012 - My 512 SSD & 256 SSD (256 SSD in CD/DVD Drive)
Late 2011 - 750 HDD from the 2012 into the 2011.

 

[sn00p]

Yes.

when I ran my 2010 MBP I had a SSD in the cd tray which contained the OS and apps, the HD in the original position held the home folders, that kind of setup requires changing settings and special modifications for FileVault to work properly:

mad it stands with your setup, you’d just second a second “Macintosh HD” drive appearing:

 

[eugegall]

I assume you've done a PRAM and SMC reset on your old machine? This could sort the issues!

 

[MarcB]

I assume you've done a PRAM and SMC reset on your old machine? This could sort the issues!

Yeah mate, Its had new thermal paste and everything.
Even if I was to have the fan issue sorted I stall dont have a headphone jack and I cant do any updates as its such an old MacBook.

At least with the one I have bought its much better specs and has the most up to date OS on it.