It is kind of disappointing I had this computer built especially for me to use as a daw, 8 cores, solid state drives fast processor 3 FireWire ports several USB ports, spent almost $3,000 and it has dropouts. So far the only way I can minimize them is to disable antivirus and set the SONAR process to above normal in priority. Which hardly makes sense to me because this computer is so fast that hardly anything causes the CPU to go above 10 %.

I can relate (but hopefully not to the drop-outs) as my 6 core (shows up as 12 with hyper-threading) cost me about $3200 to build, and I just spent another grand and quarter for four 24" screens and a big multi-monitor mount. I have been working with 4 18" monitors for over 12 years, so it was time. I'm digging the SSDs, BluRay, etc. Next weekend I move my ancient old Frontier cards over to the new DAW and will see how things go. <crossed fingers> Pretty sad, but I built the PC over a year ago and I have been deferring this move for about a year now due to my day job and not wanting to take the studio offline and having to tell the band, sorry I can't hit record it's torn apart. 
 
Getting back to you ... Did you confirm your FireWire chipset's compatibility with the Presonus? Are you using a high quality FW cable? I would keep antivirus SW and your network interface adapter off if you are not browsing the net. On my old DAW I would get random glitches using my USB based wireless during recording or mixing, when I disabled it things smoothed out. 

NYSR,
 
Check your Firewire Chipset as Eric has mentioned, but, also turn off Core Parking.  See below link for more information.    I had the same problem with dropouts on my system before turning off core parking.   You may also want to check in your System Bios to see if there are any ASUS power saving utilities enabled, if so you may want to turn them off as well.
 
http://forum.cakewalk.com/Windows-7-amp-Core-Parking-a-better-way-to-Turn-It-OFF-m1861804.aspx
 
Regards

Also, make sure you pursue the "legacy firewire driver" angle. Supposedly, if you don't roll back to it under Windows 7 you will have problems; I read that MS broke something fundamental that is bad for FW audio. 

markno999
turn off Core Parking.  

Forgot about that one, yes I did that too. Like I said, it has been about a year. 
I seem to recall that there's also a multiprocessor tweak in one of the SONAR config files that I did. 

Let's back up a little bit, and look at the settings, as well as the nature of the projects where dropouts are occurring.
 
Please provide the following information:
 
Audio interface: Sample Rate, ASIO Buffer Size
 
Sonar: Driver Mode, Sample Rate, Total Roundtrip Latency
 
Also, what sorts of plugins are loaded into the projects where these dropouts are taking place?  Some plugins are not meant to be used during tracking - they are meant for mixing/mastering, and if used during tracking can cause all kinds of latency problems.  Please list the plugins present in these problematic projects.
 
I look forward to your responding with the requested information,
 
Bob Bone 
 

I checked out the FireWire chipsets.

It took me a while to nail them down. In an add on card is a StarTech 1394 OHCI Compliant Host Controller with chipset TSB12LV21 which is specifically stated by Presonus as NOT compatible. On the motherboard is a VIA 1394 with chipset VT 6315 which is listed by presonus as compatible and this is the port it is plugged into.

I did the registry tweak to inhibit core parking.

Driver settings in SONAR indicate that my Presonus StudioLive 1602 (sometimes 1642) is using ASIO at a bit depth of 24 and a sample rate of 44.1

ASIO reported latencies are 6.3 ms input, 8.1 ms output, and a total round trip of 14.4 ms (634 samples). Dropouts occur only occasionally during playback or while recording.

Let's see if the core parking helped.

Not sure what type of motherboard you have but I had a similar problem with dropouts and glitches. After much research I narrowed this down to the Marvell 91xx SATA 6G storage Controller. I had a hdd drive and DVD drive plugged into this controller and after moving them on to the main storage controller and disabling the Marvell driver all glitches disappeared. 

If your CPU is not showing high usage, the main culprits for dropout are buffer settings (extreme high or low), or driver conflicts.
 
I honestly do not know a great deal on FW... but when I got my Saffire people here advised me specifically to disable the onboard FW if I ever got a card replacement (I never did). That recommendation to me makes me wonder if your FW card is "competing" in some way with the onboard FW. I do not know the answer to this, but given your situation I would be very tempted to pull that FW card out of the system to check things (especially since you know it is not compatible with your Presonus).

http://support.presonus.com/entries/238420-What-is-the-Windows-7-Legacy-driver-and-should-I-switch-to-it-