I haven't ever used the app (never use them) - i always use the BIOS to OC. Apps tend to be a bit heavy handed when dishing out the volts.
That said 3.8GHz using 1.3V is OK - good even - although there's a slim chance it may have hit it below 1.3V if you tinker (may not - but worth a try). I personally wouldn't go any higher than 1.35V, whatever you decide to go for - but 1.4V is perfectly safe with decent third party cooling. Some users go to 1.4V+ but the minimal gains are not worth it IMO.
I prefer a reasonable balance - a respectable clock with minimal volts. This way you get your 'pound of silicon' from your CPU and still keep things cool and quiet and most of all stable. You can push for it's maximum clock but this will require more volts, heat and for very little gain. Best to find a happy medium...
Anything past 3.7GHz and it becomes a bit of a voltage lottery - and then again, usually, over 3.85GHz. Have a play, watch some some YouTube tutorials. But if you're content at 3.8GHz - (and most would be) - then 3.8GHz @ 1.3V is a nice balance.
OPTIONAL: I would find the minimum volts it will run at 3.8GHz and then build from there - if you want to push higher again. Usually anything over 3.85GHz/3.9GHz you'll start to hit the voltage brick wall - but you may find that you can hit 3.9GHz with relative ease if you're lucky... (Again, i would stick around 1.35V and whatever GHz i could achieve - but if it was only slightly higher than 3.8Ghz - i would be happy with the 3.8GHz with minimal volts.)
Do you still have the stock cooler fitted - I can't remember? If you are still using the stock cooler don't go much higher with the voltage - your temps are good if that is stock.
