Strange jaggies appearing in RT Cuda (even on a clay material) - not so when using Adv.

[JezUK]

I'm rendering some metal pipes and I saw what I first thought was an anti-aliasing issue on metallic objects.






However, when I change the material to a basic clay type standard VRayMTL, the jaggies are still there !!






I thought it might be the geometry, so I checked the geometry, and that all seems fine, so I change from RT to Adv and the problem disappears;



This is a bug in RT ?

No 'jaggies' on clay material when using the CPU based ADVANCED renderer, but when using the GPU Cuda based RT renderer those jaggies appear.

Please advise.