Ok so my options are:
1) stick a fan in the side of my case when gaming.
2) lower clock speeds (how do i do that?)
3) set PCI-E to 101 (again, how?)
Thanks for the advice guys
Answers :
1) Put a fan on or angled at the heatsink (where power attaches basically, and this should keep your VRM's cool enough. You don't need to get excessive and put a deskfan on as suggested previously, that just indicates badcase airflow (to me, but I could be wrong).
2) You can lower clock speeds by using the program 'overdrive' inside the catalyst control centre (right click on desktop, then press properties, then overdrive. Or you can use an aftermarket 'freeware' program such as ATi Tool or Ati tool tray (I personally think ATI tool is better as gives more voltage options). I don't think this will help though, but worth a shot.
3) You set the pci-e frequency in the bios when you turn on the pc (press delete or F2 (it will tell you when it boots up)). It will probably be under the same section as CPU overclocking/freq/multipliers. You can set the pci-e freq to say, 99/101/109/110/115. Try 101 first though

For some reason a lot of boards don't like the default 100Mhz, for reasons unknown. BF2 incidently it particulary sensitive to this problem, and will cause severe texture artifacts (triangles, stretched textures across screen etc).
I initially thought my pci-e freq problem was temp related as it would run ok with fan on 100%, even though temps were still within very low range. It was way too loud and it was a corsair rep that suggested the pci-e freq change. Sorted my problems completely. Please be aware that this might not be your problem, just a possible solution.
extra 4) The psu's efficiency will degrade over time due to aging components (as will the gfx cards efficiency), so will be putting out less power and more heat than when it was brand new. It could be that the seasonic was above the threshold to run the card, but now it has dropped below that threshold. If it is an old unit (out of warranty), then leave it for a day to totally discharge of power (leave for a few hours with plug in wall so earth supply, then unplug and leave the day. Will stop you electrocuting yourself). Then take apart and clean out the fan, heatsinks etc of dust and check the fans are working ok
extra 5) Your drivers might be corrupt. Uninstall all ati stuff. Boot into safe mode and use the program (once installed in normal mode) called Driver cleaner pro, and remove anything ATI related. Restart and install latest (7.10 at present) catalyst drivers. Reboot, and check for problems.
extra 6) Last resort if not in warranty. Check the Thermal paste under the cooler. This may have dried out over the time you have had the card, and you may need to clean up the old stuff and apply some fresh stuff on there (easy to do). The reason being, that if it's dried out, it won't conduct the heat very well from the core on memory chips. I think however the memory chips have pads on them, so unless the glue has gone and the pads have come away, I kinda doubt its this.
Matthew