Optiplex 790 Tech Guide 

And yes, the 790 can run 64-bit Win10.  Sounds like you know some of your stuff already, that 32-bit won't recognize more than 4GB RAM.

You won't get free support from Dell doing upgrades, even if it's charitable.

You might find refurb parts on the Dell site, but will likely get better deals on Amazon and ebay, even for brand new stuff.

To save money, yet get a lifetime warranty, I suggest A-Tech RAM.  It's what I use myself.  Crucial also has a lifetime warranty, but is more expensive.

I don't recommend ever getting a used or refurb SSD.  SSD's are limited to a number of writes.  Even though vast, I've seen trouble on this forum with used SSD's.  I also don't recommend Kingston.  Though a bit slower, HDD's still have an unlimited number of writes.  Hybrid HDD's can be as fast as an SSD, but are expensive.

As long as you're upgrading, I suggest replacing the size 2032 CMOS battery if it hasn't been done in the last 5 years.  When I bought a refurb 790, it was the first thing I had to do with it.

Hi  bradthetechnut,

Your answer was useful, confirming that the Optiplex 790 is compatible with Windows 10.

Your suggestion regarding the CMOS battery is generally good advice, too, albeit one I had already thought of.

Thanks.

I refurbished the PC extensively, to ensure that the PC can perform well in its new role as a Family/Homework computer, now and for several years to come. I added the following hardware to the computer:

• 8 GB DDR3 to expand the total RAM from 4 GB to its current 12 GB;            
• TP-Link 300 Mbps Wifi dongle to allow internet access via Wifi;                   
• Logitech C270 HD-Webcam 720p/30 fps to allow video conferencing;        
• 18 AWG 90 degree power cable for the monitor (cable was missing);         

Besides the hardware additions, I re-flashed the BIOS to the latest supported by Dell for this computer, updated the operating system from 32-bit Windows 7 to the very latest 64-bit version of Windows 10 and updated the missing serial port driver.

I didn't replace the HDD with an SDD in the end.  It will always be possible later anyway.  I noticed that the PC was the Desktop model, rather than the Small Form Factor model.  Plenty of possibilities to enhance the PC later, should it be necessary, and any future repairs should be easy.

I think Dell should be proud of having produced a PC with such a long useful lifespan.

Hi speedstep,

I found your statement that there are zero versions of "There are ZERO versions of Windows that allow changing from 32 BIT to 64 BIT or the other way round" rather odd.

I think you mean (or ought to mean) that it is not possible to do it in place.

Your advice concerning the Windows 7 drivers, and using them for Windows 10 was useful.  I was able to restore the serial port using the Windows 7 driver.

Thank you.

Hi redxps630,

Thanks  - a very good answer.  I added another 8 GB, the PC should be good for a few years yet.