[webdev77]

I will have the following drives available for storage.

2x80GB Intel SSDs (Sata II, not Sata III, already owned)
1x512GB M.2 NVMe SSD
2x4TB WD Black or Gold HDD

The 512GB drive will be my boot drive. I will install most of my games and programs on the M.2 drive but will probably have to install a few programs on standard HDD due to lack of space on M.2. Pictures, video, and documents also stored on standard HDD but that's a minor detail (don't need fast access to these). 

So, I would like to use the 2x80GB SSDs as cache/accelerators. The second 4TB drive will be a backup drive for all other drives. 

Any thoughts as to how to most effectively make use of the above hardware? My initial thought is to use each as a cache for each of the two HDDs, but I'm not sure this is the best method. I could also add a third HDD and put them in RAID 5 instead. 

I'm very open to ideas at this point.

[Xycon]

I would use one of the sata SSD for Windows, and pretty much windows only. IF windows ever clunks up you can just format it and re-install without losing anything else. We all know how much a bitch it can be to setup things to your own personal settings and "work environment".
There not not much else to do with an 80GB drive otherwise.

Use the 2nd 80 GB SSD for regular programs like browser photoshop etc. Maybe windows page file as well, if you use such at all. And maybe a game or 2 depending on the games disk size of course.
Then use the M2 for the main/bigger games.

Use one of the HDD for temp storage with downloads and all, to not waste SSD cycles.
2nd HDD backup purposes.

Putting a SSD cache on an SSD drive never made much sense to me.
In general I dont like games to be on the same drive as windows, as a format means I have to redownload/install them all over again. Sure the m2 is faster then the sata, but when it comes to just running the OS ... I personally dont need it to load those 2 seconds faster.

Hell if my Windows would break right now or somehow be infected with something, I just format and install OS again, relink the game paths from other drive, and im good to play again in less then 20 minutes. My browser with addons and userscript and all, will still be 100% intact.

[webdev77]

I think you misunderstood. I mean using each 80GB SSD as a cache for each 4TB HDD. I can't install windows on a small SSD anymore anyways due to issues with programs that require being on the C: drive and are >30GB.

I'm not concerned about needing to reinstall Windows. I have never reinstalled an OS since the days of Windows XP, so I don't see that being a problem for me.

[Xycon]

"(don't need fast access to these) "

Then there is no point in making a cache for it either IMO.