ch341a bios flashing succeeds but still the motherboard is dead - Page 1
Forum section: electronics / repair

author: playfsx
author_rank: Contributor
timestamp: June 13, 2020, 08:05:13 am
content: Spending the night troubleshooting i can't figure out what's wrong.Here is what happened: I saved a overclocking profile at my motherboard (msi z77a-g43) for first time after 8 years of ownership. After rebooting i noticed in the bios the menus had visual artifacts, which indicated some sort of instability or data corruption. This couldn't be from the CPU overclock since im running my i5-2500k 4GHz at winter and 3.8Ghz at summer for 8 years now and the overcooking profiled i saved was the settings of the 3.8GHz. Barely an overclock when the boost by default is 3.7GHz. My first thought about the artifacts was to just reset the settings to the default and reboot. Doing that i noticed that the fans are spinning for 30 seconds and the system reboots over and over again. This is where the troubleshooting session began:-I cleared the bios didn't have effect.-Disconnected all devices including keyboard disk and monitor. Nothing.-I removed all but one ram and tried all slots one by one. Then i repeated with other 5 ram modules i had. (3 of them was the ones i usually used and 2 that known to be in a working condition but was used at the moment at the system) Didn't help.-I reseated the cpu. Nothing.-Changed the power supply. Same behavior.-Did a backflip. Ok maybe not the last one since im still alive-Finally i thought the possibility of the bios have corrupted somehow, since i believe the overclocking profiles being written on the same space as the bios.--I had a ch431a programmer in hand and connected it to the jspi1 connector in the motherboard in order to read the data from the chip. The Bios chip is the windond w25q64fvsig. Didn't work. I couldn't provide enough power to saturate the 3.3v in the motherboard with the programmer and the motherboard didn't stay open long enough to read or write.( A note here is that the programmer was connected with a electrically isolated laptop.)--So i desolder the chip and managed to read it. Some parts matching with the bios i downloaded some others was completely different. I read it a second time to make sure i wasn't reading garbage and got the exact same copy back. Then flashed the original bios from msi and solder it back and nothing! I desolder it again checked for the data integrity and i had an exact match. I put it back checking carefully the joints still didn't boot.Im a bit baffled now, can it be that the corrupted bios killed something in the motherboard ?Is any other steps you may have done to resolve the issue or at least understand what is wrong ?I don't have extra CPU or motherboard to test which of the two is misbehaving, is any other way let's say with an oscilloscope ( I have a 2ch rigol 200mhz) .Something i notice is if i don't connect the cpu i have the same behavior as if i have connected and the same as well if i don't have connected the bios chip.I uploaded a short video with some extra information:

author: playfsx
author_rank: Contributor
timestamp: June 14, 2020, 05:35:43 pm
content: Update 1:Just check the spi bus on the motherboard and is not having any data, spi clk also is dead, just a pulse while the board starts at 3.3v and then goes to ground again. If there is communication with the chip what im sure there will never boot, what should i look next?Update 2: I remove the heatshink and force power in the board by shorting the green wire(24 pin mb adaptor) with ground and the cpu doesn't get hot. So no power is going to the cpu ?

author: aqibi2000
author_rank: Regular Contributor
timestamp: June 15, 2020, 09:01:43 pm
content: So you flashed the bios and it still doesn’t work, why does this call to be the title of the post if you’re not sure of the problem?Anyway, you won’t get CPUVcore unless you have fulfilled all of the SIO requirements.To help verify it’s not an issue with your BIOS or SIO you should look to first confirm you have all of thr 3V3 and 5V0 Always present voltages, then measure for #RSMRST (3.3v) which will tell you if it will attempt to start the boot process.You’re jumping the gun, CPU voltage is literally the LAST thing in the power sequence