Matsonic MS7177CT (ECS P6VXAT) - another weird problem

[Rainbow]

This board seems to work fine. I power it up and it works. But after a while (a minute or two) it hangs and north bridge starts to heat up (so it's really hot to touch). Then it does not work at all (no POST codes) until it's powered off for some time and cools down. I've found a 1000uF cap with a hole punched in its top near 2.5V regulator - replaced it but the behavior is still the same

[Chris1992]

Re: Matsonic MS7177CT (ECS P6VXAT) - another weird problem

Checked for failed mosfets? Overvolting the NB can cause it to heat up like that.

[Rainbow]

Re: Matsonic MS7177CT (ECS P6VXAT) - another weird problem

The 3.3V power goes from PS, the 2.5V power is provided by regulator with 1 mosfet. I've checked the 3.3V and 2.5V voltages and they are OK (or at least they look OK).

[AK0R]

Re: Matsonic MS7177CT (ECS P6VXAT) - another weird problem

Has the board been recapped? From what I've seen of other posts, ECS boards tend to be very finicky, functioning best with low ESR caps. This could also be a symptom of excessive ripple voltage or insufficient reserve capacity, either or both of which would result from bad capacitors.

[Chris1992]

Re: Matsonic MS7177CT (ECS P6VXAT) - another weird problem

AK0R is right and what is the NB on this MB? I wonder if I can find specs such as vNB online.../

[Rainbow]

Re: Matsonic MS7177CT (ECS P6VXAT) - another weird problem

No, the caps are original - OST for CPU and G-Luxons elsewhere. They all look perfectly fine, no signs of bulging.
The chipset is VIA 694T + 686B. Datasheet says that 694T runs on 3.3V. The power inputs are:
VCC - 3.3V
VSUS - 3.3V
VCCA - 3.3V
VCCQ - 1.5V/3.3V for AGP
VTT - 1.5V
I wonder what the 2.5V is for...

[Rainbow]

Re: Matsonic MS7177CT (ECS P6VXAT) - another weird problem

I did a small test. Removed the heatsink and checked the north bridge temperature using my fingers.
Turned it on, let the POST go and reset. This worked for maybe 10 or 20 times, chipset was only warm. Suddenly, it became hot and did not POST any more.

[Rainbow]

Re: Matsonic MS7177CT (ECS P6VXAT) - another weird problem

I put a 92mm fan there and it seems to work fine now...

[AK0R]

Re: Matsonic MS7177CT (ECS P6VXAT) - another weird problem

You haven't fixed the problem, only compensated for it. Sounds like there is no or not enough thermally-conductive grease between the northbridge and its heatsink. The board would certainly be better off recapped, too.

[Rainbow]

Re: Matsonic MS7177CT (ECS P6VXAT) - another weird problem

It was only a temporary solution. These heatsinks are attached using some kind of sticky tape.
I suspect that the chipset is bad because it runs really hot even with the fan. I have one more board of the same type and it runs much cooler.

[AK0R]

Re: Matsonic MS7177CT (ECS P6VXAT) - another weird problem

It was only a temporary solution. These heatsinks are attached using some kind of sticky tape.
I suspect that the chipset is bad because it runs really hot even with the fan. I have one more board of the same type and it runs much cooler.

Sticky tape? How thermally conductive can that be? Sounds like it's hit or miss on whether the heatsink makes adequate contact with the chip. If you can find some thermal grease, provided there's a more positive method of attaching the heatsink to the chip (clamp, bracket, etc.), you'll probably find that the boards run much cooler and are more stable.

[Rainbow]

Re: Matsonic MS7177CT (ECS P6VXAT) - another weird problem

I don't think that it's a problem with thermal conductivity - the heatsink gets hot.

[Chris1992]

Re: Matsonic MS7177CT (ECS P6VXAT) - another weird problem

More than likely it's a bad NB chip. No experience soldering BGA so I would recommend to replace the board.

[MD Willington]

Re: Matsonic MS7177CT (ECS P6VXAT) - another weird problem

The K7S5A from ECS had a similar problem, a lot of people modded the chipset heatsink aka extruded POS held on with double sided tape...

Here is a pic of my chipset heatsink mod, heatsink and fan off of a K6-II.

[Rainbow]

Re: Matsonic MS7177CT (ECS P6VXAT) - another weird problem

Weird, I've seen many K7S5A boards but never with a problem like this.