Be very, very careful.
If the grease between the chip and heatsink contains silver, the alcohol could dissolve some of it. Then it can run down onto the motherboard, and short out various circuits. Plain raises hell with a MB.
And, if you decide to replace the MB, and have a little of the stuff sticking around, and get a bit on the socket or chip, you can burn out the chip.
I'm one ASUS MB and one AMD 64 chip the wiser for this.
I've found a powerful vacuum necked down to the fine point with bristles for the first-over, and then blowing it out for the rest keeps it running pretty cool.
Along with a 2 pound heat-sink.
Arf