vmod works fine, but i wasn't able to increase the performance at the moment. will try that next week with new cooler and ram chip coolers.
when setting vmem under 1,85V, i wasn't able to go over 1000MHz without errors.
I'll probably do some testing next weekend.

btw, my card is a reference one. got it in the end of november. i expect the perfect vmem for my card will be around 1,94V, but maybe this changes when the ram chips are getting cooler