Some of the power that allows wizards and priests to let spells pass into the physical world is the same power that allows psionically endowed individuals to let the power of mind pass into the physical. So, if a spellcaster is also psionically endowed, some of the spell points will be shared with psionic strength.
If a classical spell caster has psionics, all of the caster’s spell points will be common with psionic strength.
For example, a first level classical magic-user has a 30 psionic strength. The player then rolls 6 spell points.
Each time the character uses a spell point, a point of psionic strength is lost as well. Likewise, if the character’s psionic strength ever drops to the character’s current spell point level, each point of psionic strength used also reduces the spell points available.