Way to fix artifacts?

I've recently got a lot of artifacts after hovering on the buildings, in both Napoleon and Empire. However, I didn't get this before, with the same computer... It's not gamebreaking, but really annoying.

Here's a screen:

Spoiler Alert, click show to read: 

My specs:

Intel i7 860 @ 2.80 Ghz
HD 5670 @ 1 GB
4 GB RAM DDR3
Windows XP 32-bit
Screen resolution 1280x1024, very decent for the game&card. I tried lowering the settings (I was used to ultra), but nothing changed.

Clean out your case lately? It could be heat related.

Oh, I haven't done that since...well, my PC is still under warranty, but I'll try to use the vacuum cleaner from outside. Thx

May want to monitor your temps and voltages, too. With it still under warranty, now is the time to get it fixed.

Is CPUID trustworthy, because that's what I'm using to monitor them. I can guess what the normal temps should be (max was 80° in+game), but I don't know anything about voltages (I also hate Physics at school).

80C is a little high for many cards. Mine goes almost black, then. Many swear by CPUID so I'd say trustworthy.
Post your voltages. We can have an educated guess, then.

Ok. I played a NTw battle with only a few units and no more artifacts! But instead I had lag

I took pics for more info. The "after" numbers are a bit lower than they were in game, of course.

Since it's under warranty, I'd like to know why the +12v leg is only pulling 8.5 volts at the most. That is the one for your graphics card. It would be a good question to ask the computer's builder.

Sorry for being a n00b, lower voltage means lower power by any chance? Also, could it be the outlet's or power supply's fault?

I'll see what I can do about the store, but too bad it's Easter right now.

It is usually the power supply. If you're only pulling two-thirds of what it is supposed to be, something is not right.

I think you're going down the wrong road here. I had this issue about a year ago with a HD4870X2. Back then in my CCC I set AA to narrow-tent or wide-tent, my memory fades, and this fixed the problem. See http://techreport.com/articles.x/12458/6

Thing is I have just bought a HD6970 and the problem is back, but only for Napoloen. Empire and Shogun 2 are both fine, but I have the exact same issue as the pics above again. The issue is that after installing 11.4 drivers and CCC I no longer have the option to change my AA filter algorithm. What can I do?

I thought about changing drivers back and see if I can change AA to wide-tent to fix the issue, but DX11 comes out for Shogun2 soon and I have been playing Empire and Napoleon until then so as not to spoil my first campaigns...

Anyone know how to change AA to wide-tent in the new CCC?

EDIT: Ok I fixed the issue by turning off AA in the game menu, and in CCC I enabled morphological AA, also selected enhance application settings, edge-detect samples:12xEQ - in game doesn't look too bad and the particles are gone (these were only appearing over buildings anyway).

Hope this helps someone, and if anyone can find how to set wide-tent AA on CCC 11.4 I'd be very happy.

EDIT2: Hmmm, I may have been wrong. I turn AA back on ingame, but click volumetric effects, and the isseu is gone too. I think it is volumetric effects... if i play with them turned on and any other settings the dots go over buildings go away. I guess I will have to have them turned on.