Ok, I'm running an Antec 1040 and when I first installed my sk-6 (replacing a cheap Coolermaster) my temps didn't go down either. You need to install 2 more fans for intake in the front in that case so you have 2 blowing in in the front and the one blowing out the back. The fans in the power supply are there to cool the psu, not the case. They won't do a whole lot for your case, especially with the stock psu fans. Take my word for it, I've tested by replacing the fans in my power supply. Thats a big case that needs more fans to get air moving through it.
You can't just say your temps didn't go down when you added the sk-6. Thats my point. The sk-6 is better BUT ONLY if you have excellent air flow. If you don't, it won't be an improvement at all. Just opening the case may not do it either. I had 3 fans in my case (not including the psu) and I got an improvement by adding a fourth. Then I put in some dust filters and I even notice my temps go up several degrees when the dust filters get dirty. You have to get fresh cool air moving through that heat sink. The copper just holds heat otherwise.
One other thing to check if you are going to reseat it is don't overuse the Artic Silver. You really don't need much. I wrap my finger in plastic wrap and smear a very thin layer on. And I mean thin!!! Extra does not help, it hurts.
Lastly, I also tried an 80mm fan and found that it didn't work as well as a 60mm. I tried 80mm with and without a funnel. The 80mm moves more air but has less pressure. It also has a bigger hub in the center so if you're not using a funnel, more of the air leaks out the sides instead of being forced through the heatsink. I can't stress enough, you have to move lots of air through that heat sink. Thats why everyone runs delta fans on them for the very best performance. In fact, if you're not willing to work on airflow, it is probably not the best choice of heat sink. Others work better in situations with less air flow.
And you still haven't told us what your chipset tems are.