Fluctuating FPS

I've searched everywhere I can for a solution to my problem.
In game, it doesn't matter where I am, what I'm doing, or what I'm looking at. But, at intervals of about approximately 5 minutes (varies), my FPS go from a comfortable 15-20 to .09-1.5 and stays there for another 5 minutes or so, until it decides to resume normal function. In the mean time, it appears as if SL is taking up most (if not all) my CPU usage. Literally up to 98% usage. But, then not all the time. As the FPS were at .09 and SL was only using 40% of CPU.

I've updated my graphics driver (nVidia 8500GT), cleaned out any dust from the computer (just in case), did a clean sweep of the computer with 3 different malware/spyware removal programs, and made sure that nothing is overheating. The problem has yet to be identified.

Can someone help?

Are you on a laptop, one going into battery save mode or something similar?

Nope...sorry..forgot to mention. I'm on a Gateway GM5626 PC. No laptop. Also, this is happening with absolutely no other programs running in the background (that I can see anyway). THOUGHT it might be my web-browser taking up too much memory...but it appears that's not the case.

Hmm I have a gateway pc similiar to yours. Gm5266 I think. I have seen it do what you are seeing when it overheats.
There are some free temperature monitoring softwares out there. I use one called Everest. The copy I use also shows me the CPU speed(via the multiplier). Which gets turned way down when things get too hot. Try monitoring temps to make sure no "cool down" thing have been triggered.

Finially, and carefully, rip the front cover off the case and clean out the front fan and vents. I was amazed at all the fluff that built up in there.

Is it when someone beams into the sim? There are times on certain sims when people beaming in and out cripples the sim processor for a second or two - which, in turn, slows down the rate it sends you your frame updates, which in turn slows down how many FPS you are getting. So it might not be on your end at all. (NOTE: Rebooting the sim seems to fix this problem for a few days at least - but once that sim has the issue, it does tend to keep coming back - something about MONO scripts and how they work when they are rezzed - in this case as parts of attachments people have on).

Could be something on your side too - but try and keep your mini map open and when you feel the bog down - look up quick and watch to see if a dot appears or disappears on the map. Chances are you will find a correlation.

That's a good suggestion on the monitoring of the temps. I regularly clean it out. Matter of fact, just did today. When I opened it up to go blow out the dust. It felt actually very cool inside the housing. When FPS goes down, or so I've seen in many other blogs, it has SOMETHING to do with overheating. I'm just very hard pressed to say that this is the case with this computer.

I'd open up the task manager and sort the process list by the 'CPU' column.

/me would bet good money that you have a virus scanner or something waking up every few minutes and chewing up the CPU time that SL is usually munching on.

thanks for the suggestions, really. But as I stated before, I have absolutely nothing running in the background. That is what is bugging me. Having my task manager open, it shows only SL and SLVoice running. When my FPS go down, it's as if SL has completely taken over my CPU space. It shows SL up to 98% of CPU.
As for someone TPing in and out of the sim...I am familiar with this concept as well. That is but a brief pause in game performance until the avatar has been placed fully in the sim, and I'm quite used to that sort of thing happening.
What is happening is this: It does NOT matter where I am, or what I'm doing, or what I'm looking at. It happens on all sims. It happens no matter what I'm wearing. It happens when SL is the only thing running on my computer. I can be simply sitting in a chair, talking with someone, and my FPS go from 15 down to 0.9 and stays that way for 5 minutes or so. Without warning or my intervention, the FPS come back up to 15. Then about 5 or so minutes later, it goes back to 0.9.
It's as if my computer is 1. All of a sudden trying to process the graphics through the CPU, or 2. Something is trying to assert itself behind SL. Which doesn't make sense if the Task manager says SL is the one running so high. Of course, I'm getting all my in game information from the statistics window (cntrl-shift-1).

Er.. SL will try to take as much CPU as it can - running snowglobe, my CPU is maxed out pretty much all the time.

/me wonders if this is some weird problem related to NOT running SL in multiple-threads mode..

I'm sorry, you going to have to expound on that a little. I'm not familiar with what you are talking about with "Snowglobe" and not running it on multiple threads. Nothing I've done would have changed the way SL ran from when it was first installed, and it's never taken up that much space on my CPU. I guess, I'm not familiar enough with that terminology.

I think you are going to have to try some kinda of monitoring software like Everest. Watch temps and clock speeds and other stuff to see what is changing when things slow down.

You mentioned you changed some drivers. Was this before or after? I have seen new drivers do bad things with OEM(gateway or whatever) cards. Like not turn fans on! Might be worth sourcing the driver right from gateway or even whatever discs your puter came with.

My best guess from a distance is hot graphics card.

*sighs* I think you're right in that last bit. Just downloaded a couple temp sensors which say my GPU is running about 125 degrees C. Not good. Pulled it out, there WAS some crudded dust on it, but I think maybe the fan blew out or something. I don't think it's running anymore. Well, there's a couple hundred dollar fix I can't afford right now. LOL.
Thanks everyone for your help!

wow! 125 C!

Try using the drivers from the gateway discs that came with your machine, or try rolling back with device manager. I am thinking that the fan not working is driver related and not the actual fan. =)

hopefully free fix =)

google evga precision and turn your fan speed to 100% when playing SL. my 8800gts never comes off 100%. 125c is cooking that gpu