Still working through Red Faction Guerilla (now much more enjoyable since I swallowed my pride and lowered the difficulty setting) when I hit an unexpected blockage. I was doing the final mission required to liberate a region called Oasis when my frame-rate dropped from it usual acceptable level to 1 frame per second freeze frame.
My first thought was to turn down the graphics detail but even running in a small window at minimum detail level doesn't help. Next pop open Windows Task manager to check memory usage. The game never uses more than 1.5Gb of my 3Gb installed. Memory is not the issue. Look at CPU usage however - both cores of my 2.2GHz Athlon 64X2 are running around 90% usage in normal game play and the intensity of battle during this one mission with multiple explosions, vehicles and enemies just pushes the CPU usage up to the 100% mark. At 95% CPU the game is still playable. At 100% everything freezes.
I'll probably be able to squeeze out enough extra clock cycles to finish the game by shutting down any background programmes but really this signals the end of the road for my 2005 vintage gaming PC. I build my own computers and I always try to build in longevity. I have found that with careful selection of motherboard and components followed by regular housekeeping and maintenance, and a few judiciously selected upgrades I can stretch the useful gaming life of my machines far longer than could be expected from a pre-made model. In fact the pattern is quite predictable. The graphics card is the first thing that needs to be replaced, then memory needs to be upgraded and after that I find myself running out of hard disk space. All of these can generally be addressed with reasonably priced mid range upgrades. When the processor itself starts to complain though you have reached the end of the line. Even if I could still find a faster processor for my ageing motherboard the performance gain is likely to be negligible. A new motherboard is really what is required and that means a complete rebuild.
Just in case you are wondering about the oldest component in my rig - Its a 2002 vintage Creative Soundblaster Audigy. It still works great and gives much better sound than on-board audio.