75 degree's is absolutely fine. VRM's can take a fair bit more temperature abuse than CPU's and the ones on Sabertooth and Crosshair V boards are amongst top quality on motherboards. Rather than having a temperature range in which they work best at, VRM's come with a maximum temperature which you cant exceed. Usually VRM's throttle before they reach this temperature, so your safe (in terms of VRM temps) if you want to push your overclock a bit more.
The temperature limit is not universal and is specific to the quality of the VRM's. The way to find it out, is to find their manufacturer and check their website. I have had many motherboards in the past, ranging from low end asrock ones to top end Asus ones, the asrock board's VRMs had a limit of 90 degrees, while my current boards have a maximum limit of 130C. Usually it is between 100 and 130, but as i said before, your VRMs will throttle before that and this is a maximum upper limit not a target, lifespan of the components and surrounding components are at risk near these temperatures.
VRMs don't produce much heat, its just they have very little cooling if you don't have a custom loop. This is fine in most cases as a little bit of airflow from a case fan or just from the CPU cooler does wonders, however if you are ever seeking a bit more VRM cooling on your Sabertooth, just direct a bit of air towards it. Your VRM temps are fine, personally i try to keep mine below 90 degrees, though usually this isnt even an issue whether i consciously make an attempt to cool them or not (I have one board with custom watercooled VRMs and 2 other boards with no active VRM cooling).
Your CPU temp seems a little high though. Is that your core temperature or your socket? If it is your core, as you probably know, the general rule is to keep it below 60. Sure it probably works great but in a few months time, you will probably need to pump the Vcore up just to keep the same clock due to stability. Normally i would say that at full load, these temps are fine because no one usually puts their CPU under full load outside stress tests and especially for an extended period of time, however since you use your computer to render, i would say that lowering your CPU temps might be worth the speed reduction.
Is your temperature monitoring program, the Sabertooth's thermal armour sensors program?
What are your temps showing on Coretemp and SIW or some other programs like that?
If you want to cure your concerns on VRM and CPU temperatures, upgrade your air cooler to something bulkier with more air flow, the air flow around your VRMs will drop temperatures and you will have a bit more room for your clock due to lower CPU temps.
