IPA as in Isopropyl Alcohol aka rubbing alcohol or Isopropanol.
There may be a bit of truth to what Vince said.
For example, you can put your hand into liquid nitrogen without any harm whatsoever but only for a very short period of time (half a second or so). This is due to the Leidenfrost Effect. In relation to the liquid Nitrogen, the cores are extremely how (your hand would be too) especially if they are heated up before hand. When the liquid Nitrogen contacts the CPU heatsink there are many micro bubbles forming between the metal and the liquid Nitrogen. Essentially the liquid Nitrogen is not coming into direct contact with the CPU. However, the liquid Nitrogen is still cooling the heatsink for a few seconds before the heatsink is cool enough for the liquid Nitrogen to contact it directly, cooling it further.
Edit:
You can see this effect for yourself at home by heating a pan on your stovetop on max temp settings until the pan is essentially the same temp as the flame, then dropping a little bit of water on the pan. Notice that the water moves around almost without friction, this is due to the water riding on air bubbles and not coming directly into contact with the pan.