A month or two ago, I replaced my processor and was having a really difficult time getting the heatsink back on -- turns out one of the little pins was split in half and not fully entering its socket. Anyway, I did a really dumb thing and started applying pressure to the pin with a screwdriver, which of course skidded off the pin and across my motherboard.
Once I was able to open my eyes again, I inspected the damage and noticed that the blue surface of the PCB had been gouged to reveal something lighter underneath. It is a small gouge and I honestly can't tell if what I am seeing is metallic or just whitish. But it does appear to be right on top of one of the printed circuits. If an actual photo of my board would help, I can try to take one, but for now I'll point out the general area of where the gouge is.
It's in the pink circle above the ram slots. I don't know enough about the physical makeup of a motherboard to know what the circuit is going to, but based on its close proximity to the CPU I'm guessing it's connected to it.
I guess I should ask my question now - What do you think would happen if I had severed a circuit? My machine seems to be running OK, but every little problem I notice now makes me wonder if it's from the gouge, as if it caused some subtle performance problems. At one point I had some complete freezes that would last 3-5 seconds ... I think they went away once I made Vista stop putting my hard disks to sleep. And now I get random freezes that I think are related to a Firefox update, but ... you can imagine how much worse every problem seems when it's possibly because you damaged your own hardware. So if one of you comes along and says "a severed circuit would have killed your motherboard" then I can take comfort in the fact that my problems are probably just caused by my substandard operating system.
I did try to run some diagnostics in Sandra but I didn't really know what to look for.
Some info about my machine in case it's needed:
Motherboard: Gigabyte 965P-DS3
Proc: C2D E8400
4GB RAM under 32bit Vista
Chances are, you'd probably have a complete failure (total instability or won't boot at all) or it'll work fine. Usually the PCB of the motherboard has a coating over it to protect it from outside sources, etc. Hopefully that's all that scraped off.
Of course an actual photo of yours would be best for someone to look at. I'm not super technical in regards to your particular question.
It seems reasonable to say that your 3-5sec pauses were in fact due to Vista and it's power saving features (i.e. putting drives to sleep). As your hard drive reactivates, your system will pause as it waits for data.
And Firefox crashes on my computer all the time (completely at random, though only seems to do it with Java based sites). The recent couple updates haven't cured my issues.
It's possible you damaged some important pathways for CPU/Ram, but it's been my personal experience that when a PCB is damaged by gouging or scraping, there is no "well it works kinda sorta but with problems". In my personal experience the boards I've seen with damaged PCB's just plain don't work. They won't boot up, or scream all sorts of errors just trying to boot into windows.
I would also have to imagine that if somehow the machine is functioning but the gouge did indeed cause some serious damage, you would most likely see something a hell of a lot more than a few small random glitches.
If Sandra isn't reporting any mem errors, I probably wouldn't worry about it. Just to put your mind at ease maybe perhaps run Super Pi for a few passes, if nothing comes up, again, I wouldn't be too concerned.