Member Avatar for DrJames

I have just bought a Gigabyte GA-K8VT800 Pro Motherboard and am installing it in my machine. It has both a power fan connector for the case and also a system fan connector which both state that they are for the cooling fan.
Which one am I best using? Is the second one for a second fan?
I have bought an AMD64 Athlon 3000+ processor. Will I need a second fan or is one sufficient? Would I need one in and one out?
Thanks for your help
James

PS There is a separate connector for the CPU heatsink fan

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  • Latest Post Latest Post by ian_tec234

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A short, practical summary and what to do next.

As noted, the CPU fan has its own header and that must stay on CPU_FAN. For chassis/case cooling use the SYS_FAN header when you want the board/BIOS to monitor and control that fan; the GA‑K8VT800 manual shows the board reports CPU and SYSTEM fan speed and that the CPU_FAN header is rated (max current) by the board. (manualslib.com)

About the PWR_FAN header (what and were getting at): historically it was for a PSU fan tach or for a fan that should run at full power. On many boards PWR_FAN simply gives a constant 12V (no BIOS speed control) or is only used for monitoring a PSU fan lead if the PSU provides one. That means you can plug a second case fan there, but you may lose BIOS control or RPM reporting. (superuser.com)

Practical fan setup for an Athlon 64 3000+: a good CPU cooler plus one well-placed case fan is often sufficient at stock speeds. If temperatures or GPU load are high, add a second fan so you have a clear intake (front/bottom) and exhaust (rear/top). Aim for front intake, rear/top exhaust for predictable airflow and dust control (use filters on intakes). (noctua.at)

Quick checklist / tips

  • Plug the CPU cooler into CPU_FAN (mandatory). (manualslib.com)
  • Put your primary case fan on SYS_FAN so BIOS can monitor/control it.
  • If you must use PWR_FAN for a second fan, expect full‑speed/no control on many boards. (superuser.com)
  • If adding many fans, use a powered Molex hub or splitter (do not exceed a header’s current rating; consult the manual — CPU_FAN rating shown in the manual). Test a header by swapping a known good fan if the BIOS shows 0 RPM or issues a fan‑fail warning. (manualslib.com)

This covers the differences and gives a safe, BIOS‑friendly wiring plan while keeping airflow and dust in mind.

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Member Avatar for alc6379

The system fan connector is for your Chassis fan. The Power fan connector is primarily used to fan speed monitoring on the PSU, I think.

Member Avatar for ian_tec234

thats it most probably...but in some cases system fan is where the northbridge fan gets its powe. 3 pin.

and intakes on the front and exhaust on the top or the back. with neat wires i think your case will have good airflow... and dont forget to use filters. dust can be real nasty and accumulate on parts you dont want to have them and are hard to clean

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