Changes in volume change total force?

Pressure=Force/Area

If you had a cube, with a volume of one cubic inch, that means that each side would be one inch. As a cube, it would be like a die, and therefore have 6 sides, and 6 square inches.

800 lb/sqinch=force/6sqinches

or

force=(800lb/sqinch)*6sqinches

Force equals 4800 pounds

So now remove a side of the die, and put another die on. Four sides with 2 square inches, and 2 sides with 1 square inch is 10 square inches.

Pressure=4800 pounds/10 sqinches

Pressure then equals 480 PSI

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However, according to Boyle's law, as you increase volume, pressure decreases inversely. So since the volume doubled, the pressure should have been halved.

Can someone explain why this didnt work out? I am putting money being a problem with my force value, since that force is only a mass, without an acceleration. However, there are no other units in that equation above, so I am confused. Is force changed with volume when it comes to pressure? And if so, is that because the acceleration is somehow changed during compression/decompression?

Thanks!