Bad DIMM slot on old ASUS M5A78L-M LX Plus

[tj2]

I'm looking for some help with an inexpensive used ASUS M5A78L-M LX Plus board I got recently. I'd like to max out the RAM at 16 GB, but one DIMM slot works and the other does not. With one 8 GB stick it only boots with the RAM in the outside slot, and if I put two 8 GB sticks in, only 8 GB total are seen by the BIOS and OS. I don't see any obvious physical damage to the board--no shorts or bad solder. Does anyone have any ideas on what to look for and what I might do to fix it? I suppose that the most likely thing is damaged contacts within the slot. I don't like the idea of unsoldering the old slot and putting in a new one, assuming that I can find such a thing, but I'm game if necessary.

[DynaxSC]

Re: Bad DIMM slot on old ASUS M5A78L-M LX Plus

Hi

I'm afraid this motherboard does not support more than 8GB memory in total.
See manual.

[tj2]

Re: Bad DIMM slot on old ASUS M5A78L-M LX Plus

Hi

I'm afraid this motherboard does not support more than 8GB memory in total.
See manual.

I'm aware of that statement, however it's false according to several forums and at least one Amazon review of the board--where several people have successfully used a total of 16 GB--and, in any case, the board won't POST with one 8 GB stick in the slot closer to the CPU (or even a 4 GB stick), but it will POST with one 8 GB stick in the slot further from the CPU. It'll POST with an 8 GB stick in each slot, but only see one stick. It seems to me that there's something wrong with the closer slot. A BIOS update didn't change anything either.

[DynaxSC]

Re: Bad DIMM slot on old ASUS M5A78L-M LX Plus

If so, the only things which come to my mind are:

1. There might exist different revisions of the board
2. Some pin/pins in the CPU is/are bent, check them carefully, especially the half of the socket near the memories. Memory sockets rarely get broken.
3. Memory timings/supply voltage - maybe experimenting, if Bios allows, could help.
4. Use a DDR socket tester, compare both sockets, can be bought on Ali...s (China), are quite cheap.
5. One momory Dimm broken ? Probably not, but could theoretically be the case.
6. Try to setup memory step by step: 1. Bios reset 2. Boot with one dimm. 3. Power down, insert second dimm 4. Power on.
7. Not sure about AMD boards, but on Intel boards updating Management Engine (ME) of the chipset (an internal chipset control SW, kind of chipset firmware), if available on vendor site (usually done with BIOS update, sometimes there is dedicated sw for it). If for some reason, the ME is not updated (or even missing, eg. due to replacing the chipset), and there is no dedicated SW to do this, the only way is to downgrade the Bios to first version (using a HW programmer), and then go the full bios update path. If ME present/working, you should have in Windows Device Manager under System Devices a device called "Inter(R) Management Engine Interface #1"
8. Maybe there is some modded Bios, or a Bios modder for such kind of board Bios. Also a Bios from a similar but one generation higher board may work, but this is already an atomic solution - you need to have a HW Bios programmer, eg. CH341, and this can be risky, as well as it might require to add to the Bios the older CPU codes (also not sure how AMD hadles this). Win-Raid is a good forum to look for such solutions.

[tj2]

Re: Bad DIMM slot on old ASUS M5A78L-M LX Plus

DynaxSC, Thanks very much for the detailed reply!

1) Surely there are different revisions of the board, but I don't know about them or if it makes any difference.

2) If this were an LGA socket, this would be a great thing to check, and fairly easy. (I work on mechanical watches, so I have tools to see and manipulate very small objects.) But the M5A78L-M LX Plus supports AMD processors, not Intel ones, and the socket is an AM3+ PGA socket. I'll try spraying the socket with contact cleaner. The board did arrive looking a bit grimy, so there is a reasonable chance. My CPU is in good shape, but I should also check its pins carefully.

3) I didn't know about DDR3 socket testers. I'll see if I can get one on AlieExpress. I've never ordered from them before.

5) I have swapped DIMMs around, so both DIMMs work in the far socket and neither one in the near socket. In either permutation the board only sees 8 GB.

6) Already tried this, several times with different DIMMs. No joy.

7) There's no Intel Management Engine on this board, but I hear that AMD has something similar that I know nothing about.

8) Probably a different BIOS is not needed as I have a known-good 4 GB DIMM that also isn't seen when it's in the near socket. At first I thought the board was totally dead because it wouldn't POST with the 4 GB DIMM in the near socket and the far socket empty, but then I tried it in the far socket and it POST-ed and booted my OS. Fortunately, the 8-pin DIP BIOS is socketed(!) so it could be changed out if it ever became corrupt.

I'm running Slackware, not Windows. I don't know much about Windows except about installing it for other people. My first OS, about thirty years ago, was NeXTstep 3.2/Intel and then I migrated to Slackware Linux and, for a while, OS X on a laptop, since it is--or was--NeXTstep underneath.

I'll take another look at the board as soon as I get a chance.

Ted

[tj2]

Re: Bad DIMM slot on old ASUS M5A78L-M LX Plus

A minor update...

I took out the CPU and cleaned the socket well with quick-dry electronic cleaner and let it dry.

I inspected the pins of the CPU and all are straight and line up nicely. I booted with 16 GB of ECC RAM but the system still only saw 8 GB, so I took out the RAM and put in two known-good 2 GB sticks of non-ECC RAM. Now the system only sees 2 GB of RAM. No firmware update or special hardware version should be necessary to see this full amount and kind of RAM.

I'll have to test the socket with a tester, but that'll likely take weeks to get such a tester from AliExpress.

Meanwhile, I'll see if I can inspect the pins in the non-working DIMM socket. Maybe there's some foreign object blocking some pins. I have cleaned that DIMM socket twice with quick-dry electronic cleaner, so it seems to me that it's more likely a mechanical problem rather than dirt, or perhaps something else entirely.

Mostly I'm confused. I've never seen this particular problem before. I'm amazed that the system would ignore one whole stick of RAM and still POST. It seems like that should be a clue. It's as if the socket isn't there/connected at all. I would expect the system to be confused and not POST if only some of the pins of that DIMM were connected. I wonder if the DIMM is getting power.

[foshland]

Re: Bad DIMM slot on old ASUS M5A78L-M LX Plus

try this, put only one stick in that slot, work with the 2gb ones, so if you burn them will not be a big lost.

place it firmly, then push only one of the retainers a little so the stick tries to get off, if not working try again some more, then some more, my test rig worked like this until I cleaned it enough to work as spected.


Hope you understand me

[tj2]

Re: Bad DIMM slot on old ASUS M5A78L-M LX Plus

try this, put only one stick in that slot, work with the 2gb ones, so if you burn them will not be a big lost.

place it firmly, then push only one of the retainers a little so the stick tries to get off, if not working try again some more, then some more, my test rig worked like this until I cleaned it enough to work as spected.


Hope you understand me

I understand what you are telling me to do, but are you saying that this will check to see if the problem is a dirty DIMM socket? I will try what you suggest when I next have the chance.

How did you clean the DIMM socket? Did you need a small brush or something similar?

[foshland]

Re: Bad DIMM slot on old ASUS M5A78L-M LX Plus

Short answer
How did I fixed the slots? slowly cleaned them with IPA (isopropilic) and a toothbrush, 4 or 5 times.

Long story:

Well, ill tell you my story, that computer was a third PC I had and only used sometimes, so really didnt care a lot of it, then it gave me problems and left it in a corner for cleaning. After a year I took it off the case and cleaned it just with a compressor and a brush, it came back to life and I started using it as a Graphics cards test rig, but it had problems with rams slots and only worked when rams where only half pushed in. From time to time, because of gpus in and gpus out, the rams i suppose moves and i needed to reseat them and worked some other days. One day it stopped working at all, I thougt the motherboard went faulty, took everything out, cleaned it with a brush and all the slots softly with a teethbrush and isopropilic alcohol, the rams with a pen eraser and after that with alcohol too, started looking for the fault and nothing was shorted or burned, started testing the PSU, cleaned bios and didnt work nothing. looked again and tested again and it worked, really dont know why, but it worked, after that all the slots worked as supposed to do, rams fully inserted and no problems anymore.

Hoy did I fixed the motherboard? I dont know, its a mistery.

How did I fixed the slots? slowly cleaned them with IPA (isopropilic) and a toothbrush.




Maybe you can take a diagram of the cpu slot and test it in continuity mode with the rams contacs, looking for bad contacts and looking for the voltage supply of the rams in the slot. Will be slow, but maybe you find something and for sure you will learn a lot.


Hope you have luck.

[tj2]

Re: Bad DIMM slot on old ASUS M5A78L-M LX Plus

Short answer
How did I fixed the slots? slowly cleaned them with IPA (isopropilic) and a toothbrush, 4 or 5 times.

Thanks! I think that I'll try using IPA and a toothbrush a few times first before trying the partial insertion of the RAM.

Long story:

Well, ill tell you my story, that computer was a third PC I had and only used sometimes, so really didnt care a lot of it, then it gave me problems and left it in a corner for cleaning. After a year I took it off the case and cleaned it just with a compressor and a brush, it came back to life and I started using it as a Graphics cards test rig, but it had problems with rams slots and only worked when rams where only half pushed in. From time to time, because of gpus in and gpus out, the rams i suppose moves and i needed to reseat them and worked some other days. One day it stopped working at all, I thougt the motherboard went faulty, took everything out, cleaned it with a brush and all the slots softly with a teethbrush and isopropilic alcohol, the rams with a pen eraser and after that with alcohol too, started looking for the fault and nothing was shorted or burned, started testing the PSU, cleaned bios and didnt work nothing. looked again and tested again and it worked, really dont know why, but it worked, after that all the slots worked as supposed to do, rams fully inserted and no problems anymore.

Hoy did I fixed the motherboard? I dont know, its a mistery.

How did I fixed the slots? slowly cleaned them with IPA (isopropilic) and a toothbrush.

Very interesting! I find that sometimes if I let a machine sit for a long time (at least a year) without powering it up, it will misbehave the next time I power it up and I then have to take all the cards and RAM out and put it all back again to get it to work right. The contacts need to be wiped against each other to remove the oxidation, I assume.

Maybe you can take a diagram of the cpu slot and test it in continuity mode with the rams contacs, looking for bad contacts and looking for the voltage supply of the rams in the slot. Will be slow, but maybe you find something and for sure you will learn a lot.

Hope you have luck.

That would be quite educational, but also tedious! There are a lot of little conductors and my eyes are old and get tired easily. Even replacing capacitors on motherboards is getting harder.

[Mattachu]

Re: Bad DIMM slot on old ASUS M5A78L-M LX Plus

Check all the cpu pins mine did the same thing bent cpu pin was the culprit