ASUS M2N68-AM Plus - Not booting

[socketa]

Power supply is good
Changed BIOS Battery
Cleared CMOS Jumper
SB Power light is green
Tried two video cards

With no RAM, and Onboard Video (or video card), it cycles:
A) No display, and CPU fan shutting off in 3 seconds
Turn off by holding in power button
Turn on by pushing power button
B) Beeps long-short-short after three seconds (indicating no RAM?)
GOTO A

Same happens when RAM is inserted, except no BIOS beep or beeps.

Does this sequence of events sound familiar to anyone?

[socketa]

OK, it looks like the problem is solved
The connections from the RAM slots to the CPU slots were all good as far as GND is concerned
So, thinking about the odd POST code behaviour, when trying RAM in different slots, and that RAM is mostly connected to CPU, i thought to try another CPU;
and low and behold, it booted smoothly all the way through to the BIOS settings screen, straight away, with RAM in either slot.
So it was either a faulty CPU, or more likely maybe a sightly bent CPU pin that eventually ceased connecting with the CPU socket pin - since the CPU didn't want to come out from one corner - and i now see that five rows of pins near one side are on a bit of a slope.
I straightened up the original CPU pins with a credit card, so that the CPU now falls into the socket, but still with no success.
Amazing that the board works now though, after heating up the MCP three times, each for about three minutes; and once at 290 degrees celsius.

[RJARRRPCGP]

Re: ASUS M2N68-AM Plus - Not booting

long-short-short is the usual AMI RAM bleep code.

[piernov]

Re: ASUS M2N68-AM Plus - Not booting

Another dead NVidia MCP?

[socketa]

Re: ASUS M2N68-AM Plus - Not booting

That was my first thought; but i hoped that the green light, and the warm heatsink, meant that it could be OK.

[momaka]

Re: ASUS M2N68-AM Plus - Not booting

Another dead NVidia MCP?

That's what I was thinking as well.

But maybe try system with only one RAM stick and one slot at a time, just to rule out RAM socket / CPU socket issues.

I have two of these M2N68-something boards: one only works with 1 of 2 RAM slots (the second is dead, and there is silksreen on the PCB for 2 more, but they were never installed due to the mobo being a cheaper model); the other M2N68 mobo works fine and passes all tests except when a SATA device is connected - if I connected anything to the SATA board, the mobo POSTs and then hangs. That one for sure has something wrong with its MCP.

[dicky96]

Re: ASUS M2N68-AM Plus - Not booting

Asus M2N68-AM Plus Boardview

[socketa]

Changed to different stick of RAM, but still the same problem
Tried another different stick of RAM and this time it successfully went through the POST sequence to the BIOS settings screen
But there was an issue with the display
Rebooted and this time the bios settings was displayed correctly, but the display issue came back after selecting a different setting screen
Rebooted again and BIOS setting screens displayed OK

Put the previous RAM back in, and it worked OK

Then after that it wouldn't go through all of the POST, irregardless of any RAM that was used

So yeah, looks like bad MCP
... another parts board

[momaka]

Yup... bad MCP it is.... well, probably. :p

Since the issue seems to come and go when messing with the RAM, it could also be bad BGA under the CPU socket. Some 939/AM2/AM3 coolers are pretty bad about warping the board, and I have seen a few boards loose a RAM slot or too due to this. But if that was the case with your board, I imagine it would either full-not-POST or POST and work fine. The fact that there are graphics glitches, however, pretty positively sways this towards bad MCP.

I suppose before you part it out, give the MCP a good re-heating with hot air, just for fun / experiment, if nothing else. I usually do these until they completely poop the bed and show no more signs of life. If it comes back, slap a fan on the MCP HS and hope for the best. So far, the oldest "iffy" system I have like this that's been in *almost* daily service is a Gateway PC with an Athlon X2 6000+ and a GeForce 6100/6150 MCP. I found it in it's "iffy" condition back in 2014. The fact that it still work with almost daily use now more than 10 years later is pure comedy - like a case of "the very sick wife's healthy husband died"

[socketa]

Ok, so i heated it up to 230 deg C and it went through to bios settings;
but then it didn't do it again (it went back to original symptoms)
So i heated it up to 290 deg C for about a minute, let it cool down to just warm, and still the same issue (tried two or three times)
Then, after that, on next power on, it went through to bios settings screen, with no video issues
Ten successful POSTs after that
Then turned it off for half an hour and then powered on, and it's reverted back to the original issue (although once it went through all of the POST, but the video was messed up like before), and a few times it didn't even get to start POST.

[socketa]

Even more heating it again, made no difference
I think that it might be a RAM slots issue, because:
RAM in slot 2 causes the board to shut down part way through POST, and when it's in slot 1 there is that cycling (as mentioned in post #1)
If i don't put in any RAM, then it gives "No RAM" beeps
With no RAM installed in any slot, on DDR2 RAM slot 1, pin 239 ("presence-detect inputs") is shorted to ground; but on slot 2 it isn't (1.3M ohms to ground)
Removing the CPU doesn't remove this short
Pin 240 ("presence-detect inputs") is also shorted to ground on both slots
The pins in the slots look good, and there is no shorts on the mosfets that are next to the RAM slots

[socketa]

Got the pins wrong in the last post.
It's pin 123 (DQ_D25) that is hard-shorted to ground, and according to the boardview file that was linked to in this topic, it only goes to one pin in the CPU socket.
I removed the CPU, and the short is still there,
Looking into the RAM slot, the pin looks normal and is not touching an adjacent pin. And the CPU pin looks to be reasonably normal
The visible traces on the PCB are not damaged
So it has to be either a short in the RAM slot, or the CPU slot; which seems odd, because they both look OK

[kotel studios]

The pin on the underside of the mainboard isn't shorted, right?
Also you can send the mainboard photos.

[socketa]

Whoops, the initial board view was mirror imaged, so it was pin 239, and that is OK, as it's meant to be grounded
So it's probably still the MCP; but i'll check all of the RAM pins for shorts, because the CPU paste is highly conductive, and i'm hoping that some of the paste got into the CPU slot at some point in time

[socketa]

OK, it looks like the problem is solved
The connections from the RAM slots to the CPU slots were all good as far as GND is concerned
So, thinking about the odd POST code behaviour, when trying RAM in different slots, and that RAM is mostly connected to CPU, i thought to try another CPU;
and low and behold, it booted smoothly all the way through to the BIOS settings screen, straight away, with RAM in either slot.
So it was either a faulty CPU, or more likely maybe a sightly bent CPU pin that eventually ceased connecting with the CPU socket pin - since the CPU didn't want to come out from one corner - and i now see that five rows of pins near one side are on a bit of a slope.
I straightened up the original CPU pins with a credit card, so that the CPU now falls into the socket, but still with no success.
Amazing that the board works now though, after heating up the MCP three times, each for about three minutes; and once at 290 degrees celsius.