Hello @MutuThambi!
Although I do not have any experience in putting higher voltage to MyRIO, basing on specification the max voltage is 16VDC. It is not mentioned as absolute maximum electrilac characteristic, so there is small chance that it will not destroy your device, howevere I would strongly reccomend not to do so. In case of too high Power supply, basically everything can go wrong or behave in wierd, unexpected way.
Did you consider adding some Zener diode or stabilizer in place of DC/DC converter? It is really easy to use and it may save you much time,money and efford.
