3-pin or 4-pin fan?

[JServ]

Please tell me if I am correct. 3-pin fans draw from the motherboards power, while 4-pin draw directly from the powersupply, right?

The next question is...do i want the fan on my heatsink to have a 3-pin or 4-pin connector? and what about my case fans?

 

[tazdevl]

You are correct. 3 pin plugs into the motherboard, 4 pin (molex) plugs into the PSU. Your question as to which you should plug your CPU fan into really depends on your fan.

If you are using a 80MM fan or a high RPM 60MM fan (7K+)... you should plug it into your PSU for power. If you plug it into your motherboard, you run the risk of burning out the fan header on your motherboard or the motherboard itself.

The benefit of hooking it into the motherboard is for fan RPM monitoring... many people have their computers set up to give a alarm if the CPU fan dies, that way the CPU won't burn up. Fans these days are pretty reliable and failure is rare.

A good solution is here (you also need to be sure the fan itself supports RPM monitoring... some don't). It will enable the fan to pull current off the PSU and tie into your motherboard so you can monitor the fan without burning out the header. Be sure you buy a fan with a 3 pin tail. The splitter goes to the PSU for power and hooks into the motherboard for monitoring. If you don't care about RPM monitoring... just get a 4 pin tail.

Case fans plug into the PSU with a 4 pin connector. No need for fan monitoring.

 

[JServ]

The heatsink I plan to get is the Alpha 8045, and I read somewhere that it is possible to use this without a fan (although i'm not going to try this)....if this is true, it really wouldn't matter if my fan died, right?

 

[SWScorch]

if you have an AMD processor, you simply cannot use it without a fan. While the PAL8045 is quite sizeable, it still needs a fan to dissipate all that heat. If you ran it without a fan, it would probably be fine for maybe 10-15 minutes before your system overheated.

 

[tazdevl]

Scorch is right. You must use a fan with a AMD processor and heatsink. They simply run too hot and they do not have built in temp/speed scaling technology like the P4... which will crank back the CPU speed or shut down if the processor gets too hot.

You might last a short period without a fan... but you cannot run your system full time without one safely. From there we're getting into issues of heat capacitance... a swiftech would handle that situation better than the Alpha, but with the same results in the end.

If you are looking for a good fan for your 8045... head over to CoolerGuys and take a look @ the Mechatronics 53CFM/39DBA. It comes with the splitter I mentioned and supports fan monitoring. Otherwise get a Panaflo 40CFM/32DBA with no fan monitoring. Will peform well with the 8045.