MSI PM8M3-V rev. 1 - unstable gaming only

[trodas]

Re: MSI PM8M3-V rev. 1 - unstable gaming only

I choosen this mosfet as good replacement:

Vishay SUD50N02-06P

20V, 6mOhms, 26A, rise time 10nS, shutoff time 24nS
gate treshold 0.8V, gate charge 19nC

Even that at 4.5V the resistance is actually 9.5mOhms, then it is still far better that 50mOhms.
Also the mosfet can operate at 175°C, witch is pretty high.
While it is a bit slower (rise time 10 to 6, shut off time 24 do 20), the gate treshold 0.8V should compensate that a bit for the original is 1.2V... The slightly higher gate charge 19nC over 15nC should not be a problem.

I believe I found the perfect replacement, that is better than the original!


...however I would prefer that things begin to work, but they do not. I managed to replace the last remaining capacitor on the MSI PM8M3-V mobo - the 10uF d4 SMD suxxka, that have kinda horrible ESR or 3.2 Ohms:



...with a new SMD tantal-polymer KEMET 220uF 2.5V capacitor T520B227M2R5ATE015

...with have ESR around 0.015 Ohms

That should be a huge improve. Also I, out of the desperation, resoldered a bit the drain tops of there NIKOS mosfets near the AGP slot.

And result?

ABSOLUTELY NONE!

So it looks like that the mainboard was not up to the blame the whole damn time. It is the videocard that have to be recapped.


The Radeon R9100 was crashing when new SoF2 level is loading. Given that it run passively cooled on Licon caps:



...with 60 mOhms ESR one should not wonder. Rest of the caps looks quite similar, so recapping is in order, just waiting for the caps (as usual).


The PNY 6800 GT failed after a short time to run in AGP mode, going down to PCI mode and crashing after some gaming is played. Now that is serious problem, because there are just THERE caps, two of them polymers on the voltage input filter and they are Chemicon polymers.
Last one is unknown 100uF SMD cap and that it is for other that ceramic caps! I would be inclined to add some caps in the blank spots too, probably something over 100uF SMD... and I would also like to create a custom effecient heatsink for the mosfets on the card, because they do overheat a lot - GPU VRM temp 71°C: http://postimg.org/image/x9m8pl4sl/


Should I try recap these graphic cards before I try replacing the NIKOS mosfets?

[tmiha71]

Re: MSI PM8M3-V rev. 1 - unstable gaming only

Do you have kill-a-watt ?
If you do, it would be interesting to see consumption, in idle, and in game (before and after the re-cap)...

If you re-caped PSU correctly, some improvements should be seen, as lower wattage (personally I've seen few Watts lower consumption on some PSU's), or steadier draw from wall-socket (more often)... Also seen increased draw from the wall :-(( something went wrong, during re-cap)...

[trodas]

Re: MSI PM8M3-V rev. 1 - unstable gaming only

Nop, nothing like that. But I plan to getting something so I can measure the wattage drawn....

And the recap is long time done, no way to measure what it WAS before, mate

The PSU is fine, because if it was not, then we see troubles from going from Celeron 2.8GHz with 256k L2 to Pentium 4 3.4GHz with 2048k L2 But since the machine is ram/CPU/HDD rock-stable, then sure as hell the PSU is right.

But the graphic cards need recap. The R9100 is obvious with the bad caps. The 6800GT is much less obvious, but it seems that these Chemicon polymers could be up to the blame for the high temps AND instability during gaming (not to mention that at first it worked at AGP 8x and now only in PCI mode, with is SLOW AS HELL) ...

Of course it might even be these NIKOS voltage regulators, but I'm less and less inclined to believe this and more and more inclined to believe in bad caps in these graphic cards. Like I say, in few DAYS I will finish the Radeon R9100 and put it back. If it once crash, as it used to do when level loading many times, then I will consider these mosfets to replace. If it does not crash, then I will work on the 6800GT caps and heatsink on the mosfets to get there something serious, fill the omited caps and so on...

It will require creating a special heatsink just for measuring of the voltages, tough... Because under this:
http://s22.postimg.org/yjv18ii6p/PNY...eblocker_1.jpg
...you simply cant measure a thing. And when my machine is stable, then I should be concerned about power that it draw. Not a minute sooner...

[trodas]

Re: MSI PM8M3-V rev. 1 - unstable gaming only

Quick report - after recapping the Radeon R9100, I put it into my MSI PM8M3-V mobo and at first it show ram errors (heartbreaking, after so much work and so many polymers and added caps...) on the screen, so I have to pull it off and check.
Fortunately, I managed to find the bit of tin, that ended up on one of the bottom ram chips and after cleaning - hoooray, all works like a charm!

Immediatelly the card go into AGP 4x mode (!) and despite being TAD slower that PNY 6800GT, the system feels notably faster. That is, because, PCI mode DO SUXX BADLY. Therefore it is getting almost sure that the mainboard was NOT for the blame. The bad caps are in the GFX card(s), witch I indent to fix, of course.

Now is time for a clean win install and then I do more testing - mainly the play testing and longetivity under serious load. Then I might be inclined to see, if I can overclock the card a bit, despite the poor speed to start with

The lesson from all this is too early to draw, but there are only 3 caps on the PNY 6800GT, that are not ceramic: two Chemicon polymers 330uF 16V d10 SMD and one 100uF 16V d6.3 SMD Nichicon UD with 3.4V on it + some empty spaces, but that it is.

Since I was getting about 71°C on the VRM mosfets ( http://postimg.org/image/x9m8pl4sl/ ) with just the ATI tool cube in small window, then I suspect these Chemicon polymer caps are up to the blame.

Of course the cooling of these mosfets is poor, but that was unchanged since day one and the card worked well for me before, so...

[RJARRRPCGP]

Re: MSI PM8M3-V rev. 1 - unstable gaming only

Immediatelly the card go into AGP 4x mode (!) and despite being TAD slower that PNY 6800GT, the system feels notably faster. That is, because, PCI mode DO SUXX BADLY.

But it definitely don't suxx as much as an HDD in PIO!
That's probably the worst when it comes to the downgrading bull.
Windows will downgrade to PIO mode if there's ATA errors.
(More likely because of a bad ATA cable connection.)

[trodas]

Re: MSI PM8M3-V rev. 1 - unstable gaming only

Sure thing. Luckily, that does not happens to me. I even upgraded the HDDs on the mainboard to hi-end ones (system is on 250G Samsung 850 PRO 512MB cache (MZ-7KE256BW), data are on 1024G Western Digital Black 64MB cache (WD1003FZEX) ), but since both are on SATA 150, the speed hardly reaching 130MB/s

PIO mode will be a killer.

Sadly even after the recapping, after the first crash, my Radeon 9100 is back in PCI mode. Crazy... but things relatively reasonably work, so... what one can do now?!

...