MSI PRO Z690-A WIFI DDR4 doesn't start

[karlp028]

I bought a used MSI PRO Z690-A WIFI DDR4 and it does not start up at all so I started looking into what was going on. PWRBTIN makes it to the SIO, but then I noticed that PWRBTN# (e.g. PSOUT#) was shorted even before I tried to start it. At first I thought the short was in the SIO, but after some more tracing that was the only SIO pin that was shorted and I found more shorts on 3VDSW, SYS_3VSB, PCH_0P82_VSB and a couple of other PCH pins. The chipset gets pretty hot even in standby, so I'm 99% sure the short is in the chipset. I've seen a few other posts around the same problem with this board. How does this happen? Is there anything else I should look for?

I've got lots of time on my hands, so I will probably try to replace the chipset. I have not worked with anything that large before and I know it is one of the most difficult things to do. It looks like I can get a chipset + stencil for ~$35 CAD from AE, so why not?

[DynaxSC]

This happens generally on all boards, as well Intel as on AMD. In my opinion there are four main reason for failing chipsets: first is chipset quality which seems not to be as high as on processors, second are electrostatic discharges killing the chipsets very easy despite use of ESD protection devices, third is bad cooling (small radiators) and finally slightly too high supply voltages due to the chipset power vrms are not setup precisely (voltage setup resistor dividers in vrm networks are not precise enough due to bad design, part value tolerances or aging). On most of the boards the voltages on the chipsets are slightly higher than they should. With time this leads to silicon degradation. Eg. the 3,3V line usually has about 3,4V or even little more somtimes. I suppose vendors do this to be on the right side with the voltages, i.e. not to have too low voltages. Boards indeed become very easy unstable, when chipset voltages are lower than specs.

So going back to main topic exchanging chipset is as you wrote quite difficult. I wrote about it somewhere on this forum already. There are several issues to care about, these are:

1. right temperature on preheater and hot air, the range tolerance between tin becoming fluid and chipset becomes destroyed by temperature is very small (the sign of it is that the chipset carrier changes color when overheated), time should also be not too short nor too long,

2. its very easy to rip off pads under chipset, if you remove old chipset before all balls are in fluid state,

3. the boards are not happy when heated and do bend (sometimes quite strong), when removing chipset this can lead even to ripping off pads from board due to strong tensions (chipset carrier is not flexible at all), when placing chipset this can lead either to shorts between balls or some balls will not solder with pad, this phenomenon must be managed somehow,

4. a very high quality industry grade solder fluid must be used for the process, must resist the high temperature and be aggressive enough to be able to connect all pads and balls, 99% fluids sold in hobby electronics internet shops are not aggressive enough or they do not resist the temperature for lead free soldering process, so do not do the job in case of chipsets,

5. a factory new chipset must be some kind of "paired" with a Management Engine (ME), sometimes it is not easy, depends on board, bios and vendor, there is no one method how to do this, and "unpaired" ME will have the effect that board will not work fully correctly, eg. M.2 SSD slots will not work.

So I would recommend anybody starting this "chipset endeavor" to train the desolder/reballing/resolder process first on an very cheap, dispensable board, as a new chipset is the most expensive replacement part on a motherboard, and an Z690 board is also quite expensive, and it's quite easy to destroy the board and/or chipset.

Anyhow wish you good luck.

[karlp028]

Thanks for the tips. Is there an industrial grade flux and a solder paste that you could recommend? I'm not too concerned about ruining the board since it doesn't work anyway. I will definitely practice first on some old boards.

[ktmmotocross]

chipsets are hard to find working. chinese strip it from board and sell as new. as flux u can try fake kingbo from aliexpress.

[DynaxSC]

I use Kester TSF 6592, but its matter of local availability. Kingbo is good flux, but Kester is really much better, believe me. And there is also a significant price difference between them.

Regarding chipsets on AE buy better parts named "New", if you buy "Test good", these are used parts. "New" are usually slightly more expensive. Buy at shops with good notes, and selling the most parts. Used parts may not work, as some vendors like DELL or HP do burn fuses in chipsets at factory production closing, such chipsets usually will not work, as they are personalized for one specific board/bios image. These fuses are permanent, cannot be reset.