departing from the scope of the present invention in any of the embodiments pressurized fluid may be provided by any source including one or more pumps in communication with a fluid reservoir and may function with or without a heat exchanger embodiments of the present invention offer several advantages over card retainers of the prior art for example because the force exerted between the card retainer and the card results from fluid applying pressure over a generally uniform area the force exerted on the card will be relatively uniform thus the card will be held with uniform friction across its edges further the bladder will conform to any irregular surfaces of the chassis or card when pressurized further evening contact pressures the flexible bladder by nature is also less likely to cause damage to the chassis of the cooling system and or the cards during installation and removal processes the possibility of the card retainer u201c sticking u201d or not releasing is also eliminated as once fluid pressure is reduced there is no mechanism by which the bladder may continue to apply a force on the card further still due to the cooling ability of the bladder heat is removed from both sides of the card as opposed to a single side in conventional card retainers moreover because coolant can be brought as close as possible to the card edges i e as close as the thickness of the bladder thermal.