Why does my Dell Optiplex 755 smell like burn!?


Apr 30, 2016
I was playing Halo Custom Edition on my 755 and all of a sudden it turned off and restarted! It's smelled like burn 20 mins after it turned on again. I opened it up and the psu didn't smell bad and the mobo obviously didn't suffer any damage. BUT there was thing that caught my eye...THERE WAS NO FAN! Could it be that it overheated and it turned off by itself to prevent damage but I doubt that. Something seems fishy about the fact that it smells burned. Hopefully it's okay and no damage is done. Also it's a mini tower.

Crappy PC SPECS:Intel Core 2 Duo E4400, ATI Radeon 6450, 160gb and 1tb hdd and cheap Dell psu.

PSU Specs: Input: 100-120V ~/9A 50-60HZ
200-240V ~/45A 50-60HZ

Output: +5V ===/22A Max -12V === /1A Max
+5V (FP) === /4A Max +3.3V===/17A Max
+12VA ===/18A Max +12VB ===/18A Max

Combined Power on +3.3V and +5V Rails not exceed 150W.
Combined Power on +12VA and +12VB Rails not exceed 264W.
Max Continuous Total DC Output Power shall not exceed 305W
The fan is hidden in a housing in front of the computer. Don't stick your fingers in there to see if it's running. Because of only one fan in BTX it's big one! They will draw blood.
The fan mounting is located in between the hard drive cage, and the floppy cage. behind that , also hidden is the CPU cooler. If you start the computer with the side cover off you should feel air coming out behind the CPU cover. If there is no air then the fan isn't running. You will need alcohol wipes, thermal grease (TIM) and a 6" Phillips screwdriver to investigate further.
To remove the fan you must first remove the CPU cooler assy. This exposes the CPU which must be cleaned and have the grease applied before the cooler goes back on.
Remove any wires across the top of the cooler asy. Then loosen 2 screws at the front of the cooler from above. The cooler swings up and back and then lifts out.
You will be looking at the back of the fan. There are 2 levers you need to find to release it. One is by the HDD cage. Push it towards the fan and slide the fan back a little on that side. Lift up any wires that are in between the Motherbaord and fan. It needs to move there before it lifts out. The next lever is very hard to see. It's at the bottom of the fan assy. by the FDD cage. It needs to be lifted up so the cooler can move back on that side. It's about 1/4" sqaure and black like everything else there. Slide the fan back against the MB and lift it out. The fan wire is connected to the MB behind the HDD cage. There is a lock on the plug. The fan is held in with rubber "rivets". Sqeeze them with needle nose pliers while pressing gently on the fan to remove it. Any computer recycler should have plenty of these. The Delta AFC1212DE is the best one if you have a choice. Be sure there are no wires under the CPU cooler when you bolt it back in. They need to be pushed down in front of the MB.
Here are some suggested upgrades while you're in there. E6700, CPU. If you have or get the copper cooler P8353Then Q6700, X6800 become possible. If you want more then cooler D9729 bolts in and QX6700, QX6800 become options. The 6800s run 2.93Ghz base speed and the X chips can be overclocked in software. Be sure and get the latest BIOS update from Dell. E6700 and Q6700 are pretty cheap. If you get it fixed it can run a GTX750Ti. See the crappy computer in my sig. iI was built in 2006.


Question from WhatAreYouLookingAt : "Dell Optiplex 755 SMELLS LIKE BURN!!!"

If the fan really isn't there then you need to get one. The Dell fans are special they have a 5 pin plug with their own pinout. Get a Dell fan. They're a differnt size and power from normal computer fans. If you try another fan you may damge something due to the wrong wiring, Or it will give a fan fail message that has to be reset in the BIOS. The Dell BTX fans range from 1.2Amps to 1.7Amps 12V. Normal fans are .2-.3Amps.