XPS 1645 GPU Overclocking observations

So I decided to overclock my 4670 using Rivatuner just for fun. I was monitoring the GPU temps to make sure it stayed a few degrees below 100C, I wasn't sure how long it would last. I bumped up the clock and memory by 10% each, and played around with Furmark and a couple of games. Pretty much exactly a 10% increase in fps in every case.

Now the interesting part. There was not a single degree change reported in HWMonitor with the 10% increase while gaming compared to without. I played for about 30 minutes not-overclocked and only hit a comfortable 89C on the GPU. Then I cleared the HWMonitor values and played for 45 minutes with the overclock, and hit the same 89C on the GPU. And yes, the 10% increase in fps was real. Is this normal? Is there any good reason not to overclock it?

I also noticed that setting the clock values in Rivatuner seem to stay at the values picked until manually changed, but with no overclocking the values clock down from 675/800 to about 220/300 when a high speed is not needed. Is there any easy way to just change the "powerplay" speeds to a higher value but still let the GPU figure out when it should clock down when it is idle?

 

I can't think of one, besides dealing with Rivatuner Profiles or setting the values manually every time you want to change the GPU values.

Overclocking may shorten the GPU's lifespan a little bit, but in general enthusiasts such as yourself (probably most forum readers as well) are power users and already push the system more than the average person, so there's really no way to know what caused the GPU to fail, if and when it does. My laptop GPUs always fail and I never overclock, so maybe I should just try to get the most out of my GPU just like yourself.

Lastly, I remember reading that Dell's latest stance on Overclocking is that it will not void your warranty, unless the part fails while it is overclocked (instead of the expected "if it was ever overclocked your entire computer warranty is void"). They also recommend overclocking with a Dell support representative on the phone (obviously never do this). Seems quite humorous. If I find the link I'll post it.