In some ways, this is a nonsense problem.
At this pressure at a temperature of around 3000-3500 K, you can actually get synthetic diamonds by HPHT method. But even under standard temperature conditions at such pressure, the ideal gas equation does not apply to any real gas, e.g. the volume of helium (most similar to ideal gas) when changing pressure from 100 to 500 atm (note - the pressure is 12 times lower than given by you) at 100 K decreases volume 3.4 times instead of 5 times and at 600 K - 4.6 times respectively.
At higher pressures, these deviations from ideal gas behavior will be even greater.