dunno if it will be enough, but thermaltake makes a fanless notebook cooler that is a pad that has some wierd salt substance that turns to liquid when heated ( so as for the liquid to flow around the pad and make the heat distribution more even)
I had one of those for a few months under a circa 2007 Dell Inspiron ...with a bottom air intake.
I remember it lowering the average CPU temps by about 2C (don't remember other components values). It could be enough if your fan is just past the threshold where it starts to ramp up. Was also comfy when using the computer on my lap as there was no burning spot.
Since I rarely moved that laptop while it was sitting on my desk I then experimented with using a 1cm-thick square jigsaw foam mat from the dollar store by cutting it to fit my laptop's bottom and giving it a generous air channel under the intake. Temps improved a further 2-3C if i recall. Then I gave up and just bought a simple Fellowes plastic stand, propping up the computer 3-4 inches high and giving it enough air to stay quiet under most non-intensive tasks.