As I used 5volts I first tried a notebook fan (with integrated heatsink around). it took about 150mA and was rather noisy

afterwards I tried the old server cooling fan that I've already tried with 12volts continuous supply. With 12volts it was very noisy and took about 150mA as well. But used on 5volts it was surprisingly quiet and only took 80-90mA.

Anyway, yet another effect should be considered: When I checked supply voltage at PC Card after switching to standby it dropped only slowly.

That means, FAN (driven by BLDC motor) will reduce speed until it stops. And what happenes than? I tried with lab power supply on several FAN units: some of the FANs still drew some current after having stopped below threshold voltage for rotation.

but FAN of my choice did not. It rotates until reaching ~2.5volts, afterwards it stops and does not draw current anymore. Data of selected Fan can be seen on the picture: INTEL Socket 370(?) FAN AD9526-001 040111A 12v/0.17A SANYO DENKI

Maybe low voltage behavior is not critical, as after going to standby FAN will just deplete remaining energy of capacitors for few seconds. But if you take a BLDC with a none negligible amount of current below rotating threshold voltage you should check, if current in FAN motor really goes down to zero after some time in TV standby mode.