Okay, so managed to bench single Titan X vs Single 1080 in number of games and Synthetics at like for like settings used.
System stats were same throughout. 5960x @ 4.6 Ghz, Cache @ 4.4 Ghz DDR 4 @ 2800 Mhz. Fan profiles were at 1:1 on GPU's to keep the speed constant
Titan X Settings
Stock Settings - 1316 Mhz core / 7012 Memory throughout tests
Overclock Setting - 1474 Mhz core / 8020 Memory throughout tests
1080
Stock Settings - 1848 Mhz core / 10012 Memory throughout tests
Overclock Setting - 2101 Mhz core / 11030 Memory throughout tests
Clocks can go higher on both, in fact 1080 can get near 2200 Mhz which is pretty good considering recent MSI and ASUS models failed to reach 2100, but felt this was a good number for daily gaming profile. Likewise for Titan X 1474 Mhz was daily gaming profile, could do higher for bench, but was a decent figure overall for the TX.
All tests were at 3440 x 1440. Scores below are average fps with Min / Max in brackets, though for some tests the Max / Min are pretty crap representations.
Far Cry Primal
Titan X Stock - 53 fps (45/59)
Titan X OC'd - 60 fps (52/67)
1080 Stock - 61 fps (54/71)
1080 OC'd - 68 fps (59/78)
Arkham Knight
Titan X Stock - 63 fps (47/89)
Titan X OC'd - 68 fps (48/98)
1080 Stock - 80 fps (43/120)
1080 OC'd - 94 fps (75/136)
Checked this game 3 times as that's a pretty large and unexpected jump, but results are correct!
Tomb Raider
Titan X Stock - 88 fps (70/110)
Titan X OC'd - 99 fps (73/122)
1080 Stock - 97 fps (70/116)
1080 OC'd - 104 fps (80/128)
Shadow Of Mordor
Titan X Stock - 83 fps (55/150)
Titan X OC'd - 93 fps (48/141)
1080 Stock - 95 fps (52/181)
1080 OC'd - 105 fps (49/277)
Metro Last Light
Titan X Stock - 34 fps (10/130)
Titan X OC'd - 39 fps (12/162)
1080 Stock - 38 fps (20/78)
1080 OC'd - 42 fps (14/82)
(Maxed everything on this game including advanced PhysX aside from Blur, for real world some stupid settings would be toned down)
GTA 5
Titan X Stock - 69 fps (26/147)
Titan X OC'd - 81 fps (31/134)
1080 Stock - 81 fps (23/150)
1080 OC'd - 87 fps (31/130)
Hitman Absolution
Titan X Stock - 68 fps (62/105)
Titan X OC'd - 78 fps (66/92)
1080 Stock - 85 fps (72/104)
1080 OC'd - 95 fps (78/114)
Dragon Age Inquisition
Titan X Stock - 61 fps (50/87)
Titan X OC'd - 68 fps (54/96)
1080 Stock - 73 fps (68/114)
1080 OC'd - 80 fps (68/118)
Witcher 3 - Hierarch square (same spot with NPC's)
Titan X Stock - 50
Titan X OC'd - 53
1080 Stock - 55
1080 OC'd - 57
Vally - Extreme HD Preset
Titan X Stock - 95 fps (24/190)
Titan X OC'd - 106 fps (36/211)
1080 Stock - 100 fps (32/201)
1080 OC'd - 115 fps (34/217)
Haven - Extreme Preset
Titan X Stock - 115 fps (9/263)
Titan X OC'd - 131 fps (31/270)
1080 Stock - 136 fps (29/201)
1080 OC'd - 115 (33.5/217.2)
Firestrike
Titan X Stock - Graphics score: 18596
Titan X OC'd - Graphics score: 20800
1080 Stock - Graphics score: 21371
1080 OC'd - Graphics score: 23700
Firestrike - Extreme
Titan X Stock - Graphics score: 8830
Titan X OC'd - Graphics score: 9721
1080 Stock - Graphics score: 10286
1080 OC'd - Graphics score: 11451
Firestrike - Ultra
Titan X Stock - Graphics score: 4488
Titan X OC'd - Graphics score: 4917
1080 Stock - Graphics score: 5101
1080 OC'd - Graphics score: 5624
Cinibench Open GL test for jokes
Titan X Stock - 185.42
Titan X OC'd - 194.40
1080 Stock - 192.82
1080 OC'd - 200.61
Phewww! Think I will have a breather before comparing SLI TITAN X vs 1080. Either way pretty happy with the GTX 1080. Gives it that little bump up for running 3440 x 1440 @ 100hz and with SLI does show a decent game when adding up the fps increase. Off to go put them to use in Blood and Wine