Comment by laydn

For approximative simulation, any SPICE simulator works. You'll need to know your capacitors parasitics and power supply output impedance, find a typical via's impedance, and manually compute traces impedances and board capacitance.

For accurate simulation, the actual board geometry needs to be fed to a simulator that'll compute the actual impedances. Last I checked only Very Expensive Software could do that in a user-friendly way (I had to route a DDR3 bus. I ended up being very cautious so that all traces had the same topology and the same lengths, and cross my fingers. It worked).

If anyone knows of free alternatives for that, I'd be interested to hear about it.