Yea cooling is paramount.
Try tweaking the bus speed down slightly,
and lower the Cas rating on the memory.
(in the bios you could even tweak/check the chip voltage?)
That may help the onboard chip cache.
But if its faulty then its faulty...
i don`t know enough of linux to be able to do a software workaround.
With XP for example you could change the default L2 chip cache
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session Manager
Key: Memory Management
Name: SecondLevelDataCache
Type: REG_DWORD
Value: 0x00000000 256K L2 cache ,Value: 0x00000200 512K L2cache ,Value: 0x00000400 1M L2 cache, Value: 0x00000800 2M L2 cache ...
good luck.
