Replacing stock AMD fan

[yiplong]

I have an old Athlon64 3000+ based pc that is about to be retired into a machine solely for watching video clips. It will do nothing but playback some netflix video stream, and maybe serve as a place where I dump hard drive images from other machines.
The only problem with this is that this machine is serious noisy, with the majority of the noise coming from the crappy AMD stock fan. It cannot even keep the CPU under 45c idle. I downclocked and under-volted the chip, but the situation did't improve much. The fan still routinely spins up to 4500rpm, and the temp is still in the 40s idle.
The only way to reduce noise is probably to replace the CPU fan. Now this machine is old and I don't want to spend a lot of money on it. I hope to keep the stock heatsink but just put a quieter fan on it. Any suggestions?
Newegg.com doesn't have any cheap standalone CPU fans, but do have lots of cheap case fans. In fact I have 2 of those. Any way to fix a case fan unto a stock AMD heatsink?

EDIT:

A quick search on newegg.com turned up some promising candidates, all are cheap:

http://www.newegg.com/Product/Product.aspx?Item=N82E16835103075
http://www.newegg.com/Product/Product.aspx?Item=N82E16835233022
http://www.newegg.com/Product/Product.aspx?Item=N82E16835106122

They are all under $20.

 

[Shadow703793]

1. Are you talking about the Socket 939 Athalon 64 3000+ or the Socket 754?

2. Budget?

 

[yiplong]

1. Are you talking about the Socket 939 Athalon 64 3000+ or the Socket 754?

Socket 939

2. Budget?

I don't know how much I want to spend on this, but given its age, probably not much. I would say $30-50 is the max I would spend on this thing.

I mean I don't care if the CPU runs hot, I just want it to run quiet but not hot enough to kill it.

 

[esuckq]

for $30-50 you cold get a whole aftermarket cooler. I also tried looking for a quieter fan for my athlon 2 heatsink, but had no luck. Ended up getting a new heatsink too. If you're not worried about running it hot or overclocking etc you could look at a passive cooler for complete silence.
One thing to note if you do stick a case fan on the heatsink: case fans are usually only designed for low pressure applications. CPU fans tend to be designed for higher pressure, as they have to force the air through all the fins. So if you stick a case fan on the heatsink it might not perform very well at all- be sure to keep an eye on the temps.

 

[rodney_ws]

Given the amount of money you're willing to spend and the age of the PC involved, make sure that whatever you get is compatible with more modern sockets. $50 puts a lot of really nice coolers within reach... and if your old computer just up and dies, it'd be nice to carry over that investment to your next build.

 

[Shadow703793]

1. Are you talking about the Socket 939 Athalon 64 3000+ or the Socket 754?

Socket 939

2. Budget?

I don't know how much I want to spend on this, but given its age, probably not much. I would say $30-50 is the max I would spend on this thing.

I mean I don't care if the CPU runs hot, I just want it to run quiet but not hot enough to kill it.

Assuming space is not a problem:
Xigmatek S1283: http://www.newegg.com/Product/Product.aspx?Item=N82E16835233003&cm_re=S1283-_-35-233-003-_-Product
$27 after MIR
Compatible with pretty much ALL CPU sockets including LGA1156/1366/775 and AM2&3/ S939 (but no S754 or 478)