Yeah an old 486 or Pentium heatsink/Fan is my recommended choice for low end graphics card overclocking. I got a MSI GF2MX 32Mb SDR up to nearly 4000 marks on an Athlon 800, using a 486HSF, thermal paste and some custom Ram sinks. The core speed was maxed out in coolbits overclocking tab, and the RAM was only 5Mhz from maximum.