Actually, the Volcano 5 isn't a terrible heatsink. It's only 2 degrees warmer than the Volcano 6Cu+ which has the advantage of a copper insert and a noisy Delta fan. For only 100 Mhz of overclocking you are probably fine with what you have.
You can swap in a more powerful fan and it will cool better.
I have a very similar heatsink, a <A HREF="http://www.nexfan.com/29/248.htm?692" target="_new">Galaxy GC21</A>, which actually is the same exact heatsink but with a different, 6-tab clip. My Tbird 1.0 at 1.5 Ghz it idled at 43 degrees with peaks around 50 with the stock fan. I swapped in a Delta fan and lowered those numbers to 39 and 47. Got tired of the noise (a lot of noise) and replaced the fan with a <A HREF="http://www.nexfan.com/43/425.htm?692" target="_new">Y.S.Tech TMD 70mm fan(5800 RPM model)</A>. Temps are back up to 43 and 49 but this fan is so much quieter (despite the noise numbers) than both previous fans.
I had to do a slight mod to make make a 70 mm fan fit. Not really a mod, I just rotated the fan about 10 degrees clockwise and used two extra long screws, which wedge between fins on the heatsink, to hold it.
By the way, don't plug a TMD fan into a motherboard fan header. I heard there is a 0.8 amp of inrush current which can burnout the header. My fan is powered directly from the power supply. Use a 4-pin to 3-pin (w/ RPM Sensor) fan wiring adapter
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