# Lenovo H405 Sys Fan not working



## Casualities (Nov 24, 2012)

I bought a Lenovo H405 And i've been upgrading it lately (Finally started to atleast).. There was no case fan just a cpu stock.. I added a case fan and there is a plug for system fan on it.. and plugged in i get no case fan working. when i enter my bios it says Fan 2 not operational. i'm lost on where i should even start to get this to work.


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## WereBo (Apr 5, 2008)

Hi Casualties and welcome to TSF :wave:

If the fan also has a 'Molex'-connector (as used for older IDE-drives), you can test the fan by connecting to a Molex-cable from the PSU, it will run at full-speed if working.

The mobo fan-connectors are usually temperature-controlled, so if a fan isn't spinning that area isn't hot enough to need it, but it should still show up in the BIOS unless the fan isn't speed-controllable - Are there 2 or 3 wires between the fan and the plug?


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## Casualities (Nov 24, 2012)

I tested the fan with 12v plug and it def works. there is 2 wires on a 3 plug connector which goes into a 4 pin sys fan connection but it clicks in like its supposed to be there i'm going to add a picture


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## WereBo (Apr 5, 2008)

The 2 wires are just for 12V power to the fan, the 3rd control-wire (usually yellow) isn't there so it can only run full-power from the 12V Molex. Where is the fan fitted?


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## Casualities (Nov 24, 2012)

I have it fitted on the rear of the case and plugged into the sys fan 4 pin plug I don't care if it runs at 100000% I just want it to run lol .. I provided pictures maybe someone could give me an idea of what I need to do to get the mobo to read that the fan is hooked up.. I have a pic of the mobo model number included aswell


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## WereBo (Apr 5, 2008)

The mobo can't read the fan, as the 'control' wire isn't fitted - Check the 'spare' cables from the PSU and see if there's a suitable connector to match your fan (Some PSUs have 'em, some don't), otherwise you'll need an adapter to match the fan to a spare Molex-connector, they're only a couple of $$$/£££.


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## Casualities (Nov 24, 2012)

Ok so I just picked up a 4 pin molex to sata I'm gonna just splice the sata off and use it as a connector but which wires would I use the red and black closest to the red ? Or close to the yellow for the ground ? It goes red black black yellow ..


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## WereBo (Apr 5, 2008)

The red is '+' and black is ground, ignore the yellow (That's the 5V for the SATA-drive circuitry). It doesn't really matter too much if the red-black get reversed, the fan will run backwards and you can just turn it around, if easier than rejoining the wires.


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## Casualities (Nov 24, 2012)

Thank You much for your help! I spliced the Connector removed the unused wires from the molex and all is good ! Thank you again for the insight i really appreciate it


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## WereBo (Apr 5, 2008)

You're welcome and I'm glad it works for you :grin:

If you're satisfied that all is now OK, you can mark the thread <Solved> using the 'Thread Tools' button, near the top-right of the page :wink:


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## GZ (Jan 31, 2010)

I would like to make one selection... From the photo's that you showed, the fan (in the rear under the power supply) is oriented to move air into the case...

It should be fitted to exhaust air from the case. Cool air will be drawn in from the cooling vents located on the bottom and front of the case and over the motherboard and other components to keep them cool.

By drawing air in from that point, you are only feeding the PSU's fan, which is oriented to draw air from inside the case and exhaust it out.


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## Casualities (Nov 24, 2012)

It's actually drawin air from the inside out and they don't leave you any other places to place the fan I'm going up load pics Tmr of the whole case all sides and tell me what you think inshould do ... Also ok I'm looking at mobo ATM and can't decide which one ill upload the links one is the crosshairs formula v other is a gigabyte one both are same price around 230ish both are am3+ so they will be fitted with a and fx 8350 8 core and also I will give u the rest of my specs of what I'm trying build and what ill be doing with it and any advice would be very very appreciated


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## WereBo (Apr 5, 2008)

We've a section for that :wink: - If you post your specs etc. in the '*Building*' section, the folks there will be happy to help out


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