Ram Slot Soldering

1. Ram Slot Solder
2. Ram Slot Soldering Iron

To check the new RAM wasn't defective, I tried it in slot 1, a known good slot. All 4 sticks of RAM worked in slot 1, so the RAM wasn't faulty. All 4 sticks work in every slot except slot 2 (the first black RAM slot). If I put any stick in slot 2 - old or new - the PC is dead, it won't even boot to the BIOS. Hey, I have an FX505DU and considering adding a 2nd 8GB RAM stick to the empty RAM slot and also adding a SATA SSD in the empty 2.5” slot. My questions are those. 1) Mine came with a Micron 8atf1g64hz-3g2j1 3200 Mhz ram so the closest I found was the Crucial ct8g4sfs832a which is exactly a same spec RAM (also Crucial is a subrand of Micron).

Ram Slot Solder

I have been meaning to post this for a while, here goes finally.
I have a lot of system building experience, and generally held the belief that bad RAM slots on motherboards are uncommon. The first one I encountered was a couple of years ago - I opened up a brand new ITX celeron board and I eventually discovered that one of the RAM slots was bad. The motherboard wouldn't boot with any RAM installed in one of the two RAM slots on the motherboard - remove RAM from that slot, and the system booted fine with RAM in the other slot only. (Of course I had been storing the board for long enough that it was out of warranty, but that's another story...) I suspected a bad solder joint or tin whisker somewhere on the bad RAM slot, but my soldering iron was misplaced a while ago, and a visual inspection of the underside of the board looked OK.
I have been testing more boards than I used to over the past year, and I have found a number of other boards which have bad RAM slots, so I was wondering how many bad RAM slots others here have run into on otherwise good motherboards.

Ram Slot Soldering Iron

Also, has anyone ever successfully fixed a bad RAM slot, say with a solder reflow?
So far, in terms of failure modes with bad RAM slots, either any RAM in that slot is not recognized and ignored, or else the system won't boot with any RAM in that slot, either locking up during POST or black screen before POST, sometimes with beeps. Any time I have had memtest rack up errors, I have eventually traced it to an actual bad stick of RAM, but has anyone else noticed bad RAM slots causing other symptoms?
On dual processor Xeon boards I have further findings:

• If the blue (primary) RAM slot in a channel is bad, that whole channel is unusable
• If the first blue slot for a CPU is bad, that CPU socket is unusable
• If a non-blue slot is bad, usually only that slot is bad

Does anyone else have any experiences to add?