Install 10.5.8 on a new Mac Pro

Question

can I install 10.5.8 on a new Mac Pro 2012
where can I find a list of Macs and the Systems you can use

Answer 1

Mac Pro
Date introduced
Original Mac OS X included
(see Tips 1 and 3)
Later Mac OS X included
(see Tip 1)
Mac OS X Build(s)
(see Tip 2)
Mac Pro (Mid 2012)
Jun 2012
10.7.3
10.8
11D2001, 12A269
Mac Pro (Mid 2010)
Aug 2010
10.6.4
10.7, 10.7.2, 10.7.3
10F2521, 10F2554, 11A511a, 11C74, 11D2001
Mac Pro with Mac OS X Server (Mid 2010)
Aug 2010
10.6.4
10.7, 10.7.2, 10.7.3 (Server)
10F2522, 11A511a, 11C74, 11D2001 (Server)
Mac Pro (Early 2009)
Mar 2009
10.5.6
10.6
9G3553, 10A432
Mac Pro (Early 2008)
Jan 2008
10.5.1
10.5.2, 10.5.4
9B2117, 9C2031, 9E25
Mac Pro
Aug 2006
10.4.7
10.4.8, 10.4.9, 10.4.10, 10.5
8K1079, 8N1430, 8N1250, 8K1124, 8P4037, 8R3032, 8R3041, 9A581, 9A3129
--from: 
Mac OS X versions (builds) for computers
It appears to me that you would need a boot device with 10.5.6 already installed, and to NOT be running any Westmere features (such as 6-core processors) to have any hope. Also, drivers for 5770 and 5870 first appeared in 10.6.5, so getting your displays to work may be tough.
Custom 10.6.4 or "Full Retail" 10.6.5 is much more likley to succeed.