SPS-66 on Win7 noise

I finally made time to upgrade my PC. PC is a Dell Inspiron 620 running Windows 7 64-bit with an Intel i5-2310 w/ 8GB RAM. Since I have an SPS-66 I added a LaCie Firewire 800 card and installed the TI driver. I also loaded up Sonar X1 64-bit. I have sound but sometimes I get what sounds like digital artifacts, like a rhythmic clicking sound. I get this noise periodically in SONAR X1 whether playing a midi keyboard or a mic'd guitar amp, but also even watching a YouTube video. I've disabled the sound card on the motherboard thru BIOS. I've tried switching to the Legacy firewire driver, but that didn't help. I've also tried switching the SPS-66 from 44.1KHz to 96KHz and back to no avail. I've also powered the SPS-66 from the bus and from the DC power supply but that made no difference either. It seems more reasonable that I've got something misconfigured, but I can't figure out what it is so maybe it is the hardware. I don't want to have to replace the SPS-66 since it worked great on XP with earlier versions of Sonar. I'm also reluctant to buy another firewire card just to find out it doesn't solve the problem (they're not cheap). Perhaps the firewire cable? Any ideas? Thanks.