Exceeding the +100mV Voltage Offset Limit (MSI Afterburner) - GeForce 650TI.

[Feltyham]

Hello rookie here having a blast OCing my old hardware. Currently benchmarking my old ASUS 650TI (1gb, 980 MHz GPU Clock, 1350 MHz Memory Stock)

I have my 650TI at 1.137V which is the maximum I can get it to via MSI Afterburner. 
Right now using stock cooling I can get the GPU Clock to 1220 MHz with a Memory Clock of 1450 MHz and I'm basically on the edge of stability. The maximum temps I see are around 60C, even with the stock air cooling I'm convinced I can squeeze a bit more performance out of it.

Is there any way to exceed the 100mV limit, or in order to do this would I have to do something outside of programs like Afterburner? 

Appreciate any input - thank you,
  Feltyham