MSI PM8M3-V rev. 1 - unstable gaming only

[trodas]

Today is the day! UPS delivered a 10pcs of Vishay SUD50N02-09P-E3 mosfets samples from German Vishay HQ. Hoooray!

Therefore I immediatelly went to work. First at all, there is a picture that show the "polymerization" of caps near the AGP on the MSI PM8M3-V mobo:

The remaining two non-polymer caps (Nichicon HM & Samxon GC) run at 5V, so there is no good substitute for them, but for the rest, the capacity was bumped (2x 1200 & 2x 2200uF) as well as the specs.

The yellow KEMET tantal-polymer 220uF 2.5V cap is also well visible, as replacement for the 10uF 16V SMD suxxka cap

However that did not helped, so it is a time to replace the NIKOS P3055LDG mosfets. I picked (for the start), the two, that are most suspicious: the two most close to the AGP slot - the left one delivering the 1.50V and the right one 2.50V to the AGP.
(as you remember, lowering the 1.50V voltage from default 1.55V helped considerably with stability, so it is not like I picking up on random mosfets)

Sadly, the place is pretty crowded, so I had to pull the caps off first:

And as you can see, there are new Vishay SUD50N02-09P-E3 mosfets soldered in! I did not skip on the tin, as you can see, trying to lower every possible mOhms out...

And then I soldered back and... tried the mobo. Worked right away, hooray! (with Riva TNT) Then I tried with my R9100 and it also worked well, so I pulled the machine together and now I typing on it, as you can see

But first news is bad news. There is no instant "back to AGP mode" in Win. Still it show PCI mode, so I probably have to reinstall the graphic card to get again AGP mode back, as I always had it, before the crash during gaming...
So no instant fix.

But since it crashed by playing in PCI mode too, then I first try playing, so I can determine the stability. If anyone can cross a finger or two (or even say prayer, tough I cannot believe in anything these days), it might help

Mosfets choices:
http://www.badcaps.net/forum/showthread.php?t=32872

 

[Bo$$]

Looking good!

A little prayer for you

 

[trodas]

Thank you!

However at the cursed PCI mode, I did played for 2h 30min... and... no crash.
I did not want to claim something, but... it does not crashed and I can even do printscreens! (never been able to do this before for a loooong time)

So, maybe this will be a good start.

I would like to mention one more thing. The desoldering, the left mosfet (the 1.50V one) gate did crash up, opening the package a bit when desoldering. It might be, that I was too harsh on the poor old Nikos mosfet, but... I do the same with the previous one and the legs stays and nothing cracks.
To me it looked like a structural failure... but I could be wrong. Yet if I'm right, then it would explain easily the crashing problem - once heat up, problems become... Let's see, if this will be stable, finally. I got tired and a bit having a headache from all the gaming now, so... Enough for today!

Vishay mosfets - yea! 175°C max. working temperature - that is ownage!

 

[Bo$$]

Vishay mosfets - yea! 175°C max. working temperature - that is ownage!

LOL at those temps you simply cannot lose!

 

[trodas]

Heheh... it is not the temperature, that was causing this, but damaged mosfet in the first place and then heat was a issue. The PCB would be brown, if the temps get anywhere near 100°C... but it is not. And no crash yet. Sadly, the card is still in PCI mode. Looks like that I have to grab another AGP card and see... or complete Win reinstall.
Restore backup before VIA 4+1 install (then graphic card install and Realtek onboard sound install) did not help a bit. Still PCI mode...

 

[Bo$$]

i got that Windows reinstall would be the most simple course of action, however i think a 6800GT or a 7900GTX would be a nice addition

 

[trodas]

Errrr, no. Things have sadly changed to the worse. The machine WAS stable, even it run in PCI mode, untill I tried overclock the R9100 card. Even the power requirments go up only lightly, it was enought to make SoF2 crash during gaming AND since then it does crash as before.

Now the R9100 is completely fine, perfectly recapped with top-of-the-line caps.

Therefore the mosfets that I did replaced are not the culprits And therefore replacing GFX card or reinstall cannot help, because this IS a hardware issue. It could help to regain the AGP settings FOR A WHILE - eg. untill the 1st crash, then it fall back to PCI mode again, therefore this is just a waste of the time. First it have to run stable even with overclocked R9100, witch power requirments are very very low, compared to 6800GT.

I did not have any 7900GTX (or Radeon HD 3850, witch was the fastest AGP card IIRC), so I cannot go there. But the 6800GT will be great - IF it will run stable and in AGP 8x mode. R9100 does run at AGP 4x only, witch is sad. Even lame old slow FX 5200 does run at AGP 8x ...

 

[Bo$$]

maybe get another motherboard. No way all this recapping for nothing...
Worst case you can bake it. Maybe the north/south bridge are loose?

 

[trodas]

Well, first at all, I did not have the money to get another, not even used, mainboard. So that is firt limitation. Second is, that after all the work I want to make it stable... Somewhere must be the failure and I have to find it. I can forgive the losing time and bios settings, but I cannot forgive the crashes.

And PCI mode.

Lose NB is almost out of the question. When I added my custom huge heatsink, then I used screws to hold it pretty tight on the mainboard. Since when heated up, then NB can only expand, then the pressure could be only higher. Therefore this could be almost ruled out of the question. SB? Could be, but it is not so stressed when gaming, right? And it have nothing to do with the AGP, right?
Therefore I concentrate on the NB. I would like to find, what voltage and from witch mosfet it getting and then replace the mosfet and possibly add some cap under the PCB or anywhere near the NB. That should do the trick, because I cannot think about anything else...

I did not yet get into the replacement, because I waited to response from VIA about the P4M800 working voltage, but no reply If they tell me, then it would greatly help me out finding the voltage on the mainboard... Another way is to increase the NB voltage to get more stability...

 

[Bo$$]

It is possible you've overtightened the NB?

 

[trodas]

Errrr, I wish it was that easy, but... no. It is not, simply because the bahaviour was the same before I even replaced the NB heatsink with my own huge one, then things did not improve when a huge 120mm fan is blowing air on it, so I quess that it must be something else. I got a computer for fixing and fixed it sooner by completing some components of mine there and use a 2750MHz Opteron 148 now
Much better!

But I will eventually get to it and replace another mosfets and look hard for some bad things on the mainboard...