-Portal at x:80 z:80 in Overworld teleport to x:7 z:26 in Nether instead of x:1 z:1
-Portal at x:1 z;1 in Nether teleport to x:10 z:14 in Overworld instead of x:80 z:80
-Portal at x:0 z:0 in Nether teleport to x:13 z:13 in Overworld instead of x:0 z:0
I tried on 14w11b snapshot and 1.7.4 but I think it's older..
As described in the Minecraft Wiki, portals are not connected with an exact 8:1 ratio, as they perform a search within a specific range in the other dimension.