What is the HIS iClear Card you ask? Here is what the product page has to say:
"the latest solution to video card noise reduction. It has an excellent implement of state-of-the-art design and technology and give you a better gaming experience by reducing the distortion and noise generated from graphic card. It reduces the noise distortion generated from high-end graphic card (from both Radeon and GeForce) or TV tuner card, which provide up to 10% increase performance on Signal-to-Noise Ratio"
So to sum things up, it seems that the iClear doesn't do a damn thing. As far as anyone can tell, it is simply a slab of plastic that plugs into PCIe x1 socket.
However, according to a review by Alexey Samsonov the device did have a positive effect on signal-to-noise-ratios at certain frequencies when utilised with a low-quality analogue TV tuner card and a video card configuration. But even if that is accurate, it is hardly worth spending around US$80 on (athough Newegg has been bundling them free with certain video cards apparently). Still, if you do decide to experiment with it, I highly recommend picking up Boing Boing Gadgets' X-Maple pixel-flutter reduction block for PCIe as a companion. [HIS iClear via HTSAP via Boing Boing Gadgets and iClear Review]