sfbayzfs
Active Member
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.
RAM Slots on a Mac The only iMac currently on the market with user-serviceable RAM is the 27 inch model. The 21.5 inch version of the iMac has the RAM soldered to the motherboard. When you purchase the 21.5 inch iMac you have to configure it at purchase with the amount of RAM you want.
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.
- During the PS removal I noticed the trashed PCIe x16 slot and I started to get curious. The computer seemed brand new (because it was) and I couldn't imagine a computer being sold in this condition. Eventually the kid admits to trashing the new computer.
- Hakko 5mm Chisel Soldering Iron Tip - HAK-A1052/P. Hakko 5mm Chisel Soldering Iron Tip for 455-16 Iron - HAK-A1052/P.
- Fast acting and instant wetting design allows for fast soldering. This non-corrosive, non-conductive flux is ideal where a strong, long lasting bond is needed.
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
Information about the failing memory slot on the T30 model.
Problem description
One of the two memory expansion slots in the T30s fails after some time. This is also encountered in some T2x series Thinkpads, and eventually this problem can occur in both memory slots if it is not repaired early enough.Hot weather seems to induce the failure.
Affected Models
- ThinkPad T30
- ThinkPad T20/T21 (in some cases)
- ThinkPad X30/X31/X32(in some cases)
RAM Slots on a Mac The only iMac currently on the market with user-serviceable RAM is the 27 inch model. The 21.5 inch version of the iMac has the RAM soldered to the motherboard. When you purchase the 21.5 inch iMac you have to configure it at purchase with the amount of RAM you want.
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.- During the PS removal I noticed the trashed PCIe x16 slot and I started to get curious. The computer seemed brand new (because it was) and I couldn't imagine a computer being sold in this condition. Eventually the kid admits to trashing the new computer.
- Hakko 5mm Chisel Soldering Iron Tip - HAK-A1052/P. Hakko 5mm Chisel Soldering Iron Tip for 455-16 Iron - HAK-A1052/P.
- Fast acting and instant wetting design allows for fast soldering. This non-corrosive, non-conductive flux is ideal where a strong, long lasting bond is needed.
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
Information about the failing memory slot on the T30 model.
Problem description
One of the two memory expansion slots in the T30s fails after some time. This is also encountered in some T2x series Thinkpads, and eventually this problem can occur in both memory slots if it is not repaired early enough.Hot weather seems to induce the failure.
Affected Models
- ThinkPad T30
- ThinkPad T20/T21 (in some cases)
- ThinkPad X30/X31/X32(in some cases)
Solutions
Ram Slot Solder
IBM will replace motherboards of machines under warranty.
Quite often the problem occurs first in the secondary memory slot. The root cause of the failing memory slot in T20/T30 series laptops is in fractured solder joints between the RAM memory module socket legs and the motherboard. The solder joint micro-fractures arise after a few years' use as the heavy and unsupported memory module sockets are located under the motherboard. Exposing the laptop frequently to even minor shocks or vibration (e.g. placing the laptop daily onto a table or port replicator) will cause slow fatigue to the solder joints as the memory modules are basically hanging unsupported on the bottom side of the motherboard, and all vibration will cause them to move microscopically small amounts up and down. Eventually the fatigue of the solder joints will be creating a crack on one or more joints, being visible using a stereo microscope.
Permanent fix: The best way to repair the broken solder joints in a permanent way is to re-solder all the memory module socket legs after removing all memory modules and the laptop battery. The repair can be performed either by a qualified electronics repair shop or a skilled electronics hobbyist using a very narrow-tipped soldering iron (e.g. Weller or Metcal), some liquid soldering flux needed for treating the solder joints before re-soldering them, a stereo microscope for accurate viewing of the work area, and of course a good skill in electronics soldering. Using this procedure it is often possible to save and permanently repair a Thinkpad T20/T30 series laptop without replacing the motherboard. After the solder joint repair it is a good practise to place a well-supporting soft padding (thick adhesive tape etc.) between the installed memory modules and the memory panel/door that covers the modules, preventing this problem from occurring again after a few years.
Temporary fix: The problem can often be corrected temporarily by applying pressure to the RAM memory modules, thus making a better contact in the fractured solder joints mentioned above. One way to do this is to cut a small strip of metal and fold it in half. Then tape it to the inside of the memory panel so that when the panel closes, it places pressure on the middle of the affected module. Close the door (may not shut all the way), and boot the system. The computer should regcognize all RAM again. If the primary slot fails, the computer will fail to POST, or lock up during boot. In this case it is absolutely necessary to make the permanent fix mentioned above.
See also
