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I have had an Intel LGA775-based motherboard (DG33FB) for about 8 years now, but for an year or so the LAN port was unreliable, sometimes working and sometimes not. No software solution was working, and it was an Integrated controller so there was no obvious hardware solution.

Recently a power surge (suspected) blew the SMPS, so I bought a new one. When I connected the 24-pin ATX power supply to the board (with NOTHING else, not even the CPU power connected), the entire "lower" area of the board (towards the PCI-e slots) near the ports was getting hot. By touch and an IR temperature "gun", I isolated the hotspot down to this 82566DC ethernet LAN controller (see below), which is unfortunately BGA-mounted. The chip and nearby components are apparently reaching nearly 100°C, even on standby! It's extremely likely that this was the case even before the SMPS blew, and obviously connected with the dysfunction of the LAN port. The LINK LED on the LAN port flickers under various manipulations indicating a loose contact. Don't know if the heating and loose contact are connected.

What should I do? I don't think I can just leave it like this, but a nearby repair shop said they don't do BGA (de)soldering.

Also, what is that glass-like "window" on the chip? Quartz window for EPROM erasure using UV?

Intel Wired LAN Controller 82566DC

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    \$\begingroup\$ Sounds like it's dead, Jim. \$\endgroup\$
    – Majenko
    Dec 18, 2016 at 16:01
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    \$\begingroup\$ Take it off by making a heat shield from aluminium foil and using a heat gun (a paint stripping heat gun is aggressive but since you're removing a dead IC it will be fine). I spread the foil on the PCB and push it down onto the components, then I carefully cut it with a scalpel to reveal the component I need to heat. Do this two or three times if you are using an aggressive heater. Patiently heat the IC, give it 20-30 seconds of heating it for a second or so, then pointing the heat source away for a second or so. The IC will move when the solder is wet, and often just flies off. \$\endgroup\$
    – Matthew
    Dec 18, 2016 at 16:10
  • \$\begingroup\$ @Matthew Thanks, would this protect other chips nearby, like those capacitors and the metallic thingy (crystal?)? \$\endgroup\$
    – Milind R
    Dec 18, 2016 at 16:51
  • \$\begingroup\$ @MilindR Yes, two or three layers of aluminium foil generally does not have good thermal conductivity through it, due to the low amount of contact between the sheets. \$\endgroup\$
    – Matthew
    Dec 18, 2016 at 17:41
  • \$\begingroup\$ The easy workaround, if you have a free PCI/PCIe slot, is to add an Ethernet card. \$\endgroup\$ Dec 18, 2016 at 21:16

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There are a few reasonable ways to try and save this board

  1. Remove the chip via desoldering
  2. Remove the chips power supply
  3. Damage the chip such that it won't conduct current

The easiest way to desolder the chip at home is using a heat gun. A heat gun is similar to a blow dryer but with a much higher temperature exhaust stream . If you aim the heat gun directly at the chip you may be able to lift the chip directly off the board after it heats up enough. If this device was constructed to RoHS standards, the solder requires a very high temperature before it becomes molten. Since its a BGA package, a tiny screwdriver under the corner should allow you to lift off the package if you can get the solder to melt.

Removing the power supply to just the chip would be just as good. I have no way of knowing what components power this device, but the component just above it labeled Q1LN looks like a surface mount transistor (likely a MOSFET). You could remove that and see what happens. The upside to this approach is it should be very easy to reinstall that component if the desired outcome is not reached.

The last possible solution is to simply damage the package enough that the die inside it is no longer present. Although the package is quite large, the die is likely a very small component directly in the center. Drilling directly into the center with a 1/16th drill bit would likely destroy the die entirely. However, you would absolutely have to avoid drilling through into the circuit board below. Consider this an option of last resort as this is obviously a non-reversible step.

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