Not having the sides on with your tower actually will raise the temperature of HDDs/SSDs cutting their life shorter due to no airflow - a closed tower will grab air from the front and the PSU fan (+case fan if you have that) will blow it out, generating flow that is necessary. I tested this myself, there's a big difference.
I'm not an expert, but practically speaking with SSD you will notice much faster boot up times compared to HDD and it should be faster to access the data stored on the SSD. As far as I know, there is no reason not to benefit from the improved performance of SSD because prices came down a lot in recent years. Swapping a HDD for SSD is supposed to be the most cost efficient way of improving performance on an old computer. The SSD itself is physically much smaller in size compared to a HDD. It's amazing for me that the thing can store several 100's of gigabytes of data when it's so small and lightweight.
I have no case fans, just the PSU fan, processor and GPU runs cooler like this can't see temperatures of anything else, case fans are noisy don't want that. Easier to remove the dust before I play a game from the GPU to LOL It's not heat that's the issue, it's heating up, then cooling down which is the issue, I never turn my rig off. Although it pops I'll use laptop / tablet and order the bits for a new 1, wayyyyy over due, just lazy and can't be arsed, it works. Would like to play COD though
I can tell you from the start that I have never was able to use something refurbished here really and I do not see any case of that matter anyway. I can make my own repairs though or even very very slight upgrades for that matter. Thanks anyway.