My experience: seen a 2nd hand CV1 for £450 so took the plunge as it wouldn't lose value in trying (they are now £500 New!)
1st issue is getting it connected to install as it has HMDI and your Graphics Card will want to make this the default Monitor 1 and therefore it will give you a blank screen if you had your Monitor previously on HDMI and then switch that to using a HMDI to either DVI or DP adapter for your Monitor. i.e. if you change your Monitor from the only one connected then it doesn't automatically get reverted if you change port. Some DP cables even do not allow a Monitor to be the primary one and instead require a powered type as it is also used to extend in series between monitors. So you reboot if switching the Monitor around before you then (power down) connect the Rift. It makes totally no difference if you use a HMDI>DVI for your Monitor or a HDMI>DP(4k*2k) for your Rift instead. You'll still be able to access HMDI Full Range (darkest blacks) for your Monitor which will also display in the Rift anyway as is separate to 3D settings.
Then you can install the Runtime (now 1.13) which downloads the latest update but after v1.7 it uses the SSE4.2 cpu check. My Dual Quad Xeon 3GHz failed and so it would NOT install!
Fear not - I found a link to
1.7 Runtime Install from the Oculus Forum by a game designer (as they don't bother storing old versions!) and this does not have the SSE4.2 cpu check and so auto installs the latest Runtime

You can then set "Install Unknown Apps" and "Auto Update" in Settings (only this way you can install games to C: drive)
Running through the Setup it tells you then to plug in your USB HMD, Sensors (1 is basic), Controller (a daft remote seriously when we could have used KB & M!), Gamepad (skip if not needed yet), Touch (if you want to play other cool stuff else skip if you haven't got). They suggest that you must have USB3.0 - this is false and their compatibility lies lots! It told me prior this that my cpu and Motherboard's Via USB chipset are both non-compatible. However, they did find out that USB2.0 is best for extension cables (and powered if doing so) as that can go longer than USB3.0
So I plug them into a basic PCI USB2.0 card and it did not even find them! Then I put them both onto the motherboards USB2.0 and it does find them!
I then enter my height, my eye distance, I start the scan leaning back sitting down and next I'm seeing the Dreamdeck VR Demo - WOW!!!
Next to get E

D working and all you do is start the game and set 3D Mode in Graphics to HMD Headphones. Next time you start the game it immediately starts VR and Oculus Home (also starts when you put on the HMD).
I can run E

D on Ultra Settings but set Terrain Quality & Material on High as most do and have found more detail by doing this. I now use no AA but use SS0.85 and HMD1.25/1.50 and even PPD at 1.25 in Oculus Debug (if this really has any affect now).
You'll probable want to disable ASW (it will still cap to 45fps however if it drops below 90) =
CNTRL + Numpad 1
I've only had issues on one update which required RESTART OCULUS device in OH Settings (reboot would not solve it)
Then the Win10 Updates reset my whole Drivers to become enabled which upset the whole system - I need to disable Monitor Speaker Drivers as I use a Soundcard to Studio Monitors but the Rift's Headphones are far better as they added DTS (3D Audio). It had also messed up swapping my USB Dongles (software protection) in trying to resolve issues by updates - these needed reinstalling and then my upgraded GTX1080 could be loaded after each boot finally. This only added an extra 5fps to my GTX970 which is perfect for this limited 30 to 45fps you get on this Xeon non-compatible computer.
The only issue now is the regular screen jumps and grey outs which is an Oculus Runtime 1.13 bug (everyone has) and is now fixed in their Beta version and so is about to be fixed.
So...the updates for Rift and Win10 mess with USB - as does swapping some of your devices around as they remain in its cache. Clearing that did not solve it but reinstalling copy-protection dongles does which can cause your whole PC to get bogged down with issues as I found.
All in all - you can use your CV1 on an old Dual Quad-Xeon PC if you get the
1.7 Runtime: -
https://forums.oculus.com/developer/discussion/comment/408108/#Comment_408108