You'll see a drop off in score as you bump the vga clocks incrementally, then you'll start getting lockups and bench failures as you go beyond that. At the score drop off point and failures you'll need to incresae vgpu.
At stock voltages, you shouldnt be in danger of overheating at all unless you live in Mogadishu. (long as fans are 100%.
That being said, its up to your gpu to decide what the highest clockspeed it wants to do at your givin ambient temperatures. If you forcefeed some cold air conditioner air into the gpu you'll get cold scaling beyond your sticking point without voltage increase but not much.
If this is strictly for gaming 24/7 purposes then you'll probably best off just keeping the clocks in the safe zone. Kinda like wearing ganny panties
