Can I get away with...

[bobotech]

...using 6.3 volt 1500mf caps in place of 10 volt 1500mf caps on an old msi ms-6300 motherboard?

There are 3 of them on the edge of the board and I have 4 spare 1500mf/6.3 volt caps that I bought from you a while back.

[Topcat]

Power the board up and measure the voltage on those caps. If the voltage on them doesn't exceed 6volts at any given time, it is safe to use 6.3v caps in those places.