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[Roland]

Ok, so I recently got a new machine, and had a GTX 670 in it. The behavior I witnessed was strange.. I could put everything on max, and it would run perfectly at 60 fps... for a little bit. Then, it would totally {Scrap} out, and the frame rate would drop heavily, barely able to pull 30.

I was like, "WTF? WHY U SO BAD MWO?"

However, after much testing and digging, I found the cause, and figured it may help folks.

The 670, and possibly all kepler chips, have built in throttling when temperatures get high.

Info explaining some of this comes from here.

Only, when I say "high", I mean really not that high at all... Throttling starts at 70degress. Since the card can go up to 90, while 70 was hot, it wasn't so hot that I thought it was the problem.. however, this is what was happening...

So, the fan had a really lazy speed curve by default. Basically, it would be off completely until the thing got up to like 40... then it would increase, but not fast enough to keep the card from hitting that threshold. This was exacerbated by the fact that the case didn't have really good airflow.

What happened is that the card would get hot, and then the fan would eventually kick on, but by then the case was full of heat and it would take a bit to cool things down. In the meantime, the card would bust through the throttling threshold and start getting all stupid. At 70, it supposedly only throttles down 13 Mhz, but whatever, the effect was huge... I don't think it was hitting the 80 degree throttle point ever.

Anyway, this was making everything terrible. I ran some 3dMark II tests, and was getting like 2000, instead of the expected 8.

The ultimate fix was to create a more aggressive fan curve, which basically keeps the temperature below 70, always. Now, the card works perfectly. Everything is cool.

Hopefully, this helps someone else who had the same issue with this card... I know I saw some folks who had complained about the 670 with what seemed like similar issues.