At relevant resolutions
https://www.techpowerup.com/reviews/MSI/GeForce_GTX_1660_Ti_Gaming_X/28.html
https://www.techpowerup.com/reviews/MSI/GeForce_GTX_1660_Ti_Gaming_X/33.html
TPU was unable to test the Vega 56 OC but THG did and obtained 8%
At 1080p, the Vega 56 edges MSI 1660 Ti tested here by 1%, Doing the math ....
MSI 1660 Ti = 100 x 99.0 / 90.3 = 109.63
Vega 56 = 101 x 1.08 = 109.08
So that's pretty much a wash at 1080p... at 1440p ...
Vega 56 = 103 x 1.08 = 111.24 so Vega 56 gets the edge (1.61%) here.
Looking at ancilliary data...
Peak Power: Vega 56 (237 watts) / 1660 Ti (141) ... $76 in extra electric costs at 30 hours per week over 4 years (@$0.11 pr kwhr), + $20 on PSU purchase, $10 for extra case fan
Load Temps: Vega 56 (75C) / 1660 Ti (67)
Noise: Vega 56 (42 dbA) / 1660 Ti (32 dbA)
The 1660 Ti can be had for $279 on new egg today....lowest price for vega 56 is $369... $90 more. Given the ancilliary numbers, Im thinking the Vega is now**at best** a a $259 option.
From a personal PoV, the noise is a deal killer; I've looked at the AIB versions and noise is still waaay high by comparison. But it would cost me $165.80 in extra power costs (more with AIB) over 4 years plus a more expensive PSU and an extra fan (one 140mm fan per 75 - 100 watts)