Question Maximus VII Hero doesn't POST with 12V 8-pin ATX plugged in

Mar 26, 2020
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Hello there,

as stated in the title, I'm having trouble with my ASUS Maximus VII Hero Board.
It worked absolutely fine until recently, when I tried to start my PC the power LED would come on for a second, then shut down immediately and repeat this over and over. No POST beep, no error code, no screen flicker etc.
I had an i7-4790k and 16GB RAM installed at that time. I went through all the troubleshooting I know (I'm not a beginner) and eventually ended up with just the board with nothing but power connected, no CPU and no RAM installed, used a different PSU, still the same problem, the board kept shutting down after a second. But when I removed the 12V CPU power connector, the board stopped resetting and showed error code 00 instead (both with CPU/RAM installed and without). I couldn't really verify this but i think in this case its complaining about the 12V connector missing, so I cant even verify the CPU is fine, and I have no other 1150 Board. So my guess is probably a power surge killed something in the CPU power section? I measured between the 12V and ground pins on the CPU connector and there's at least no direct short, but really it's the only thing I can think of. Any other way to test this or should I just throw away the PSU and board and cut my losses?
 

COLGeek

Cybernaut
Moderator
The answers to many of your questions are in the other thread you are participating in.

Your motherboard will NOT start without a CPU or memory. Detaching the 8-pin power connection on the motherboard, won't tell you anything either....especially without a CPU and memory.

If the CPU and memory is installed properly (and working), when connected to a functioning PSU, then your motherboard is likely the issue (defective).

Sorry, but your troubleshooting procedures are helping isolate your issue.
 
Mar 26, 2020
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Sorry but as it seems you don't get the problem right either. The problem is there with AND without a CPU/RAM installed when the 8 pin is connected and disappears with AND without a CPU installed when the 8-pin is disconnected. So the board wouldn't start anyway, the only point in removing the CPU was to see if it was defective and shorting out the VRMs or something. I know the board won't do anything without the CPU, but at least if the CPU were the problem the PSU wouldn't instantly trip anymore with it removed.

But anyway, in the end as you say the board seems to be the issue, as I suspected in my first post too. Sadly I don't have another board or CPU to test this. But I was hoping someone here might know how to search for the specific issue on the board or whether it might be fixable at all. Those boards are still quite expensive here and I don't really want to buy a new one for such an "old" CPU
 
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gtarayan

Distinguished
Mar 2, 2011
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Do your CPU and RAM function in a known working 1150 system? If you do not have one handy, you could try
to have a known working PSU properly connected to the board without your CPU but with 1 stick of RAM installed (if no go, try the other stick). If the board stays on, are you able to perform a BIOS update routine with Flashback function? If yes, experiment further, and see what shakes out.
 
Mar 26, 2020
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Do your CPU and RAM function in a known working 1150 system? If you do not have one handy, you could try
to have a known working PSU properly connected to the board without your CPU but with 1 stick of RAM installed (if no go, try the other stick). If the board stays on, are you able to perform a BIOS update routine with Flashback function? If yes, experiment further, and see what shakes out.
I've tested the RAM in another system, it's fine. No way to test the CPU since I don't have another 1150 board tho :/
With a known good PSU, the board stays on as long as you connect only the 24pin. Of course it won't post like that, but at least it stays on. I've already done a BIOS flashback this way. As soon as you connect the 8-pin CPU power the PSU shuts down immediately, this happens in any configuration (no CPU and RAM, only CPU, only RAM, both intalled)
 
Mar 26, 2020
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Have you taken the board out of the case to eliminate any grounding issues?
Yep I did.


Otherwise, all signs point to a borked board.
Yeah I was afraid that might be the case :( Any way you know to narrow down the problem to a component? If it's just a cap or something I might be able to replace it myself, a dead mosfet not so much :/ I've already taken off the VRM heatsink and looked at the components, nothing obviously fried there.
 

gtarayan

Distinguished
Mar 2, 2011
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Any way you know to narrow down the problem to a component?
Of course there is - unfortunately I lack the necessary expertise to provide any meaningful advice. I have seen youtube videos showing use of a multi-meter and an infrared camera to identify failed components, removal faulty electrical components from the board, and soldering in replacements.

Best of luck.
 

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