Lets leave it for a day or so. I will start looking into the video card. As I recall you are running a PNY 8800GTS 640.
The next numbers we are going to try for are 1320/660 and that may require a mem change to 5-7-7-19-31 and possibly a Vcore bump. If it wont do it at all, then we have hit the wall on the memory and may need to settle for what you are at now or just a touch higher @ 1312/328 until such time as you get DDR2 800 memory. Even with that, you must remember the FSB limit is always going to be there on the PN5SLI and the best you may do is 1550/775 but with tight and low memory timing which also makes a big difference.
You will need to be careful about a memory upgrade. If your BIOS only goes up to 2.1v the better memory may be a problem. You will have to shop for DDR2 800 designed for use at 1.9-2.1v and not need higher to maintain full speed/low latency stable. Usually if the advertised voltage is 2.1v, it needs 2.2-2.3 to run stable at high speed so be careful about that.
As we approach the wall on the northbridge it will heat up rather quickly with very small changes as compared to past settings. Right now you are just entering that ultra-hot zone. I dont want to cook that compound unit it has a bit longer to cure.
I was thinkin (I know, danger-danger-danger) Since he seems to be stable and the sim has improved again perhaps we can try a test now to see how bad the traffic is changing the load. If it is pulling the life out of it at airports then the test would indicate the need for a replacement AI set. I know it worked great for me because I can't live without the traffic.. it was too dull















