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How To Pinpoint Cause Of Mainboard Problems
These are excellent times to upgrade an older PC with a new faster mainboard, or just to upgrade a mainboard with a faster quad-core microprocessor, because for just about 20 Dollar/Euro these quad-cores can easily be found used but tested on eBay or Aliexpress. For instance the Intel Xeon (R) 3.16 GHz X5460 CPU was bought with one year warranty and it now already works about 2,5 years without any problem on my also second hand Asus P5KPL-AM SE computer. Which was originally an Intel Dual-Core Desktop PC.
I recently only replaced the original Dual-Core Intel Fan with a better Cooler Fan with 4 pipes, a Cooler Master Hyper H412R /AM3, which will guarantee the longer life span of my CPU quad-core. It already helped cooling down the CPU temperature by about 30 degrees Celsius! (It was about 65 degrees Celsius normally, which is close to the limited maximum). My new Cooler really makes a difference and came with both universal mounting brackets for AMD and Intel LGA775 mainboards.
That is the reason why my brother also decided to buy the same older P5KPL-AM SE mainboard second hand plus the same quad-core Xeon processor. And 2 DDR 2GB 800MHz modules were also bought for just 9.09 Euro. Below is shown his ‘new’ P5KPL-AM SE desktop computer case that is replacing his previous much older mainboard computer.
Everything worked fine until he was almost ready with installing a new Windows system with the use of his external USB memory stick. After a reboot he lost his video output signal. And both VGA (the original on board VGA chip) and neither his HDMi Video card worked afterwards. So after a long search he brought his computer to me to examine the failure. Luckily I could test his mainboard with my PC_Debug_Series_Card also known as DEBUG KING with LCD Host, MiniPCIe/MiniPCI/LPC (3-in-1 Interposer) and PCI Interposer slot card.
I used above shown PCI Interposer Card with LCD Host. After I had inserted this card and had switched on his computer it showed a running clk signal on its clk led and on its two 7 segments display an end code of “32” after it stopped changing. And on the LCD display it gave the text that it was an undefined Post error which could originate from the Ami Bios. So I took out the Winbond 25X80AV DIP8 Bios chip and flashed it with the correct Bios content from my own identical mainboard.
Which is easy with this tool: the ‘Universal BIOS Backup ToolKit 2.0.exe’. After that small program (use administrator rights to start it if you use Windows 7 or higher!) saved my 1MB ROM to my harddisk I used my RT809H to write it into his Bios chip. And I placed his Bios back in its mainboard socket.
After that everything worked again splendidly and both his computer VGA and HDMi output were back again! And I was glad it was solved. But about 5 days later my brother phoned me that he lost his Video output again after installing some new programs by using an external USB memory stick again. Apparently it looks like that these Asus mainboards are somehow sensitive to external boot sequences by corrupting the internal Bios chip in the process. Also because these mainboards are designed with an easy method to reflash a corrupt Bios. It can be done at Boot by using keys ALT-F2, or by using the EZFlash utillity, or by booting from CD or Fat16/32 USB memory stick. Which doesn’t seem to work by booting from the original Asus mainboard anyway because the DVD never boots although it is explicitely mentioned on the DVD that it does which never works, no matter which PC I tried!
So he brought his computer over and I re-inserted my PCI Debug card and switched on his computer. It showed a running clk signal led, and an end code of “E1”. And the video outputs indeed didn’t work again. So I let it reboot by pressing the RESET button on the front, and another end code of “81”appeared. Next LCD diagnostics messages are shown in full color!
Next photo shows error message BIOS 81 I got on this American Megatrends Inc. computer. Both LCD POST diagnostic messages indicate that the Memory modules and/or the Bios are at fault.So I started by removing one DDR2 Ram module from its mainboard and I concluded that if I removed the module that was closest to the EATX Power connector (slot DIMM_B1), the Asus mainboard booted again fine with working Bios boot , video output and working Num lock led on/off on the Keyboard.
I also checked out if both modules worked if only placed in DDR2 DIMM_A1 (64bit, 240-pin module), leaving slot DDR2 DIMM_B1 (also 64bit 240-pin) open. They both did so were fine! Slot DDR2 DIMM_B1 could be defect. But to rule out that conclusion I also tested both slots with my older 667MHz DDR2 240-pin modules which made no difference. And I rechecked the Bios 25x80AV chip. My RT809H programmer showed it had a verify error at startposition 0xC8AFD.
So it again was a good reason to reflash/rewrite my brother’s Bios again.
Previous RT809H screenshot clearly indicated that the Bios was corrupt again after it was compared with the original saved ROM file on my harddisk. And obviously there was nothing wrong with the 240-pin DDR2 memory modules.
Next photos show the end Post diagnostic code that the PCI inserted Interposer Card showed. First code E1 followed by code 81 after a reboot. Also good to know is that my other programmer, the TL866, completely failed to Verify this 25x80AV chip after it was programmed. It never Verified completely which was no problem for my RT809H at all!
It sure helped to have this Post Diagnostic PCI card running in this problem mainboard after the video output was completely lost! And after the Bios chip was re-inserted the Asus P5KPL-AM SE booted fine again with both DDR2 Ram modules! It all matches with the Post codes that were given.
Previous photo showed that the Windows 10 boot screen was back. And I was happy I could fix my brother’s computer again. Probably he will be more careful when using USB memory sticks while booting on these Asus mainboards that all have the EZ Flash utility which could mean more trouble if the Bios gets flashed unintendedly in the process.
But just in case his Bios chip is going bad he bought 5 of them new for 2,5 Euro on Aliexpress. And flashing/writing them outside his mainboard is never a problem for my RT809H. Which I upgraded yesterday to new version 20190418. It only took me about 1,5 hours just to log in on the bad ifixit China site because of the terrible security question I never used but couldn’t avoid. Which kept me waiting over and over for another 15 minutes until that security question disappeared and my login registration was finally accepted.
I noticed on Aliexpress a lot of new test hardware tools, including DDR2 and CPU test boards. Which were not at all expensive. Maybe they will be something nice for some future repairs. It is always nice when something that looks like a hopeless situation afterwards gets easily fixed. And again at no real cost, of course not counting time and the rather expensive programmer used.
Albert van Bemmelen, Weert, The Netherlands.
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Note: You can read his previous repair article in the below link: