Static Is Killing Me, Using The Scientific Method Options

[sfsurfer]

I'm wondering if some of you might be able to offer me some suggestions as to eliminate some static in my recordings.

My Setup:
I've got a 800 MHz G4 running 10.3.2 with 1.5 GB RAM and an Echo Mia PCI sound card which is connected to a Behringer Eurorack UB1202 mixer which has a single Shure SM58 microphone plugged into it. I'm using Deck for all of my recordings. I have all of this plugged into a UPS, which is then plugged into my wall.

My Problem:
Anytime I record with this setup, I get frequent static noises. I bought the UPS because I thought that the power from the utility company was causing the problem. After hooking up the UPS, I found no change in the frequency of the static. However, when I record using the cheap little microphone that came with my computer, I get no static on the recordings. This suggests to me that it is my setup with the sound card, mixer and microphone. What's really frustrating is that I avoided getting a USB interface for recording so that I wouldn't have the seemingly common static problems associated with USB.

My Question:
Is there an easy way for me to figure out where this static is coming from (within the sound card, mixer or microphone) without having to buy any more equiptment? I don't have access to another set of these components, so I can't just swap other ones in place of mine to test. I also can't return the sound card, mixer or microphone, so I'm stuck with them. Is there a likely culprit that is causing my problems? Has anyone else solved a similar problem? Or does anybody have a better suggestion in how to connect a XLR plugged microphone to a computer for relative cheap? If so, I've got a virtually unused sound card and mixer for sale cheap!

[sfsurfer]

Thanks so much for all the suggestions! I'll try to go through them all and explain what I've done - nothing seems to have solved the problem unfortunately.

The UPS does have voltage line regulation, so that shouldn't be a problem any longer

I am not recording with anything else plugged in to the room (no dimmer switches present either) except the bare minimum of computer equiptment that I need (CPU, monitor, mixing board).

I tested the brilliant, yet obvious suggestion of using something else as an input device. I decided to use my headphones as a microphone and plugged them in to both the mixer and the PCI card directly. In both cases, any recording resulted in static.

I don't have any MIDI equiptment hooked up to my system.

I also have everything set for the input clock as internal input (not exactly sure what that means)

I believe everything is being sent at 44.1 kHz, but I need to do a little research on my mixer to see if that's true. It is being recorded at 44.1 kHz for sure

I have tried to burn a CD of the audio and it also contains the static

I have tried other channels on the mixer, and they all have the static.

From the above testing, it appears to me that the problem is residing in my PCI card or computer since using a microphone (my headphones) directly into my PCI card gave the same result.

I've tried to adjust the buffer size in Deck, but it seems to always reset itself to 512, no matter what I set it to. I'm using Deck LE, so if anyone has experience with it and can give me some advice there if that's unusual, I'd also greatly appreciate it.

One thing that I didn't mention before is that my 3 hard drives (plenty of free disk space) are all connected to a Sonnet Tempo ATA133 PCI card since I was hoping for some faster disk performance for A/V applications in my old sawtooth. Could this be causing some problems since the input and writing to the HDs are both on the PCI bus?

I'm going to try to post some samples on a web page soon (I'll post a link here), if any of you are interesting in assisting me further by taking a listen. Thanks again for all your suggestions and I welcome any more of them.