Question Dead CPU?

Krieger0311

Honorable
Jul 12, 2012
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Hello all- I have been working with an issue on my old rig for way too long now, trying to resolve the issue on my own with the plenty of resources available. Unfortunately at this point I am at my rope's end and wasting money on this thing when I could have put it towards a new desktop. I have read and tried everything stickied here and then some, and I have built a few desktops now. PSU tests fine with multimeter, I even bought a new one on Amazon to try and returned it after the results were the same.

Specs-
Sapphire Pure Black 990FX AM3+ board
CM Silent Pro Hybrid 1050 PSU
PowerColor Radeon 7970 3GB GPU
AMD FX- can't recall if it's an 8150 or 8350 with AMD FX Asetek Liquid Cooler

What happened: Haven't used my rig for much of anything intensive over the last few months until recently before the desktop died when I started gaming again. I first noticed it wouldn't come on and was giving the code "FF" on the LCD on the board with no beeps from the built-in speaker. On powering up, fans would spin but nothing else would happen besides the "FF". However after turning it on and off 2 or 3 times I noticed a faint burning smell. After scouring the internet and various forums including here, the consensus seemed to be board or PSU problems due to the code and burning smell, and that very rarely is it the CPU but could potentially be. Going off of this I started with the PSU which is confirmed not the issue. This week I tried the board- I found a used board on ebay that seemed to be compatible with most of what I have and dropped $130 on it (These AM3+ boards are hard to find apparently!). The board I got was an ASUS Pro R2.0 which I installed last night.

However, when it rains it pours and I accidentally dropped my old CPU when cleaning the paste off of it, bending some pins. I was able to get them back into place enough to seat in the board properly, so now I am not sure if I have a "which came first" issue now- but I kept going. One issue I overlooked is that this board did not have an on-board speaker. I ordered an external one from Amazon last night but it hasn't arrived so I have no idea if there are any beeps yet. However, on boot I get similar results to my old board- fans spin, except the red CPU light comes on immediately. After a minute or so, the entire thing shuts down. I also noticed that same burning smell on the first or second power on attempt- this time since I had everything open I was able to "sniff quickly" and it seemed to be coming straight from the CPU- though I can't be sure. I find it hard to believe it's the motherboard since this would be 2 now, and I am thinking my original motherboard may be just fine and I actually have a CPU problem although visually the CPU seems fine.

One thing to note is my old board has a molex connector built-in that one of the 3 heatsink wires was plugged in to. I used a different adapter to power it now because this board doesn't have a molex connector. I am wondering if the molex is required. I cannot find a manual for this heatsink anywhere, even after reaching out to Asetek and AMD. The fans/pump are supposedly controlled by the same wire and I get spinning fans so it seems to be working, but because of the way it shuts down after a minute or so I am wondering if it is overheating the CPU, or if the machine is just shutting down because it doesn't detect a working CPU. I've ordered a molex to PSU cable to try that as well.

This morning I also ordered a cheap, $15 CPU on Amazon that is supposedly compatible with the ASUS PRO R2.0. My next plan is to just pop this one in and see if the red CPU light goes away. If it does I think I am going to assume my old board is fine and buy an upgraded compatible FX CPU to put in it as the $15 ebay one I found won't work with it.

Is there anything else I could/should be doing to try to determine if my CPU or motherboard is bad? There are just too many variables in my head now and I don't know what else to try but I keep sinking money on unnecessary parts. I am also concerned with all these different CPU/Mobo combinations. Could the current board giving the red CPU light have anything to do with the Bios version being incompatible with the CPU? or would I get some kind of other indicator/not auto shutting off first? I figured if it was the BIOS it would at least boot to the BIOS and give me a chance to change things.

ANY advice is appreciated.

TL, DR: FF Code, No POST, Burning smell with 2 different CPUs, 2 motherboards both indicate a board/CPU issue, unsure of the best way to move forward without wasting more money.
 

InvalidError

Titan
Moderator
What is the actual PSU model you have? If your old PSU had a capacitor failure on the 5VSB output, it may have fried your motherboards by sending 10+V peaks on there and you wouldn't catch those on a multi-meter unless you have a fancy one with 30+kHz min/max capture bandwidth.

BTW, simple CPU cleaning tip: remove paste before removing the CPU from the socket. That way, you don't have to worry about dropping the CPU or bending pins while cleaning.
 

Krieger0311

Honorable
Jul 12, 2012
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10,510
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What is the actual PSU model you have? If your old PSU had a capacitor failure on the 5VSB output, it may have fried your motherboards by sending 10+V peaks on there and you wouldn't catch those on a multi-meter unless you have a fancy one with 30+kHz min/max capture bandwidth.

BTW, simple CPU cleaning tip: remove paste before removing the CPU from the socket. That way, you don't have to worry about dropping the CPU or bending pins while cleaning.

Here is a link to the PSU I have-

Based on what you said I suppose the PSU could have fried the new motherboard, but I still feel like I would be getting other symptoms than I am getting. Maybe not. I feel like I am going backwards here, thinking I had finally narrowed the problem down. Hell I can't even sell parts at this point since I have 0 clue what is working and what isn't with apparently 0 way to actually find out without investing some serious time and money.

In regards to the CPU cleaning- it was still in the board when cleaned but impatience had me leave the swing-arm up and when I turned the board sideways to remove a stuck stand-off- out it went :/

Also, in regards to testing CPUs- I really don't get the best way to do this either. I updated the BIOS on my old board with the FX-8150 at SOME point in the last 5 years so I have 0 clue what version that BIOS is actually running. The new board I also have 0 clue what the BIOS is actually running since it was used.... So is there physically no way to test a CPU on these since I don't know what the BIOS, and can't flash it because it doesn't match the CPU? Ugh.
 

InvalidError

Titan
Moderator
At a glance, the PSU looks like it shouldn't be a problem.

And yes, troubleshooting when the parts you have refuse to work together for whatever reason and you have no known-good configuration to go back to for validation is a PITA. When I built a friend's Ryzen 1700 two years ago, the system wouldn't boot no matter what I tried so I sent him back to the computer store he bought his parts from to get everything tested. I was told the shop tried multiple boards, multiple CPUs and multiple DIMMs before finding a combination that actually worked. Once they managed to get the board to boot, they updated the BIOS, put the original parts back together and everything worked fine after that. Got me nervous for a while that I may have screwed something up, turned out it was something I couldn't do anything about.
 

Krieger0311

Honorable
Jul 12, 2012
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At a glance, the PSU looks like it shouldn't be a problem.

And yes, troubleshooting when the parts you have refuse to work together for whatever reason and you have no known-good configuration to go back to for validation is a PITA. When I built a friend's Ryzen 1700 two years ago, the system wouldn't boot no matter what I tried so I sent him back to the computer store he bought his parts from to get everything tested. I was told the shop tried multiple boards, multiple CPUs and multiple DIMMs before finding a combination that actually worked. Once they managed to get the board to boot, they updated the BIOS, put the original parts back together and everything worked fine after that. Got me nervous for a while that I may have screwed something up, turned out it was something I couldn't do anything about.
Sounds like I need to hit my local PC shop and have them test parts since they have more resources than I do....

Thanks!
 

InvalidError

Titan
Moderator
Sounds like I need to hit my local PC shop and have them test parts since they have more resources than I do....
Do stores still have AM3-related stuff? The testing probably won't come for free and may end up costing more than the parts are really worth.

Before you possibly shell out even more money, you may want to give it another try and triple-check that everything is connected properly. Many people rebuild PCs and get a 'mysterious' no-boot due to forgetting the ATX12V/EPS12 connector or a PCIe AUX cable.
 

Krieger0311

Honorable
Jul 12, 2012
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Do stores still have AM3-related stuff? The testing probably won't come for free and may end up costing more than the parts are really worth.

Before you possibly shell out even more money, you may want to give it another try and triple-check that everything is connected properly. Many people rebuild PCs and get a 'mysterious' no-boot due to forgetting the ATX12V/EPS12 connector or a PCIe AUX cable.
Thanks for the advice- Unfortunately you are probably right about availability of parts. I was more or less hoping they could help me narrow it down- at least rule out the PSU.

Since I don't know if my CPU was dead to start with this new board, or if it died from bending pins, or if it's perfectly fine, and also not knowing if it is compatible with the BIOS on this new board, I went ahead and found an FX-8350 that the ebay seller told me was used to test the board prior to shipping. It was on sale for $65 brand new with a free 30-day no questions asked return policy. I'm hoping this will at least tell me if I have a board or CPU problem....

I was planning to upgrade my 8150 in my dead rig to an 8350 anyway if the issue turned out to be the CPU....But now you have me paranoid my PSU may have just blown both boards :/

One last question- In regards to my CPU heatsink- the wiring is still quite confusing due to the lack of the molex on the new motherboard. It seems to be working as both fans and the light come on the heatsink, and I hear what sounds like liquid moving through....Is there anything else I should be looking for to make sure it's running properly? My thought is the CPU light on the board wouldn't immediately come on due to overheating/heatsink issue, but rather once it heats up....but I could be wrong there. Just trying to rule out everything I can.

Thanks again
 

InvalidError

Titan
Moderator
I wouldn't worry too much about the PSU. There is a whole ocean of crappy PSUs out there but the Silent Pro is along the better-end of what you can get from CoolerMaster.

Even with no heatsink attached, the CPU should still run long enough before hitting thermal trip to do the POST beep if a speaker is connected to the motherboard's speaker header or integrated on-board and put something on screen. I'm guessing the "CPU" LED is little more than a visual complement to the POST beep: gets turned on if the BIOS doesn't clear a flag somewhere within a predetermined time after reset.
 

Krieger0311

Honorable
Jul 12, 2012
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Well- good news! My $60 FX-8350 CPU showed up. Popped in the new (ebay) board and got past the CPU light issue! Now the dilemma/question is- is my old original board actually dead? One of two things- either the new board BIOS wasn't compatible with my old CPU (likely either way), or my old CPU was just plain dead.

I really dont want to swap everything back to the old board with the new CPU in case it turns out to actually be dead....but i dont like this ebay board as much and I will have to rebuild the OS due to driver and compatibility issues.

That and my old board was running the 8150, the 8350 BIOS version is likely not compatible so I may just wind up with the same issue.

Any thoughts on how to test the new CPU in the old board successfully?
 

InvalidError

Titan
Moderator
A newer BIOS usually supports all older compatible CPUs, there should be no problem with testing an older CPU model on a motherboard with newer BIOS. (Other than a slight possibility that putting a dead CPU on a working motherboard may fry the motherboard.)
 

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