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Phenom II X4 955 BE killed my M3A79-T Deluxe mobo

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April 12, 2010 6:07:25 PM

If i posted this in the wrong place I'm sorry. I am very thankful to anyone who takes the time to read this thread as I am at my wits end with this issue. The thread is this long to include as much info as possible to cut down on the questions that people need to ask me about my setup and what I have done/tried so far.

I have an Asus M3A79-T Deluxe mobo that I have been using for over a year with an athlon 64x2 6000+

When I built the PC, I just popped everything into the Mobo and turned it on without ever changing any settings in the Bios and it has worked fine since (plug n play!). I have 2 ati 4850's and so recently I decided that its high time I upgrade my CPU to bring it up to par with my GPUs and so I purchased a socket am3 phenom II x4 955 BE processor (the newer c3 rev MBOX version).

I had already done the research to make sure that this motherboard would support this CPU and according to the Asus website this CPU is supported as long as the bios is updated. I looked in the BIOS updates section at the asus website and downloaded the latest update (version 1501) which was released in December of 2009 assuming that the latest bios update would include support for all the CPUs that had been released since my Mobo shipped to me in december 2008. After flashing the BIOS with my old athlon 64x2 6000+, I verified that windows booted up and everything was working normally with the new update. After this I shut down everything to install the new phenom. I removed my old CPU and installed the new one as I have done many times before building computers for myself and others.

After installing the new CPU and putting my case back together, I switched on the power supply and pressed the power button and my computer won't turn on now. The Motherboard has a power and reset button on the board next to the cmos reset pins, and those are lit up as if they are getting power. The power supply clicks like its turning on and then immediately clicks back off. All plugged in fans (case / cpu / gpu) spin about 90 degrees before stopping. If I unplug the 4 pin CPU power connector from the mobo and press the power button, everything starts up and continues to have power (the fans continue to spin on everything, but obviously the computer won't work because the CPU doesn't have any power). I don't know if this piece of evidence will help anyone.

My initial reaction was that maybe the CPU was DOA because that does happen and so I decided the first thing to do is to unplug everything, open the case back up and then swap back to my old CPU. I dropped the old athlon 64 x2 6000+ back into the mobo and to my horror, it does the exact same thing as with the phenom installed (click on, click off). I then proceeded to spend about 9 straight hours into the night trying to troubleshoot this issue which included stealing the power supply from my HTPC to try it to eventually removing the mobo from my case and bench building it on a phonebook.

At this point my mobo is sitting on a phone book with only 1 stick of ram plugged in (tried both sticks individually in all slots), cpu + fan/heatsink, 24 pin power connector, and 4 pin CPU power connector. Same thing - click on, click off. Tried with and without a GPU (tried both of them). I am very stressed out at this point because I don't exactly know WHAT is broken. The board does the same thing whether the new Phenom or the old Athlon 64x2 is installed. I am afraid the Phenom *somehow* bricked my board, which in turn fried my athlon 64 x2 when I reinstalled it. I have asked some friends and nobody seems to think its possible for a CPU to destroy a mobo, but what do we know, we aren't experts. I am very pissed at the moment since my computer was working totally fine before and now it will not work when put back together EXACTLY how it was before I got this darned phenom.

I filed for an RMA today with newegg for the phenom to get it replaced but what good will it do to drop it back into the mobo that wont even work with my old CPU anymore. I called Asus and explained the situation to them. The mobo is still under warranty and so they said I can send it in for repair but that will take 3 weeks. They also said they won't replace anything, only fix it. I wonder what Asus is going to do when they drop a test cpu into my mobo and it gets fried.

I don't want to just accept the fact that the mobo is bad and buy a new one. The cheapest possible AM2/AM2+ mobos that I can buy WITH xfire are around 100 dollars and are crappy compared to the almost 200 dollar M3A79-T Deluxe that I've been using.

I guess I am going to send the board for repair and contact AMD to see if my old athlon 64x2 can be replaced through warranty as well. Its really going to suck to wait a whole month for everything to come back from RMA only to have it not work still.

Anyone have any ideas?
a b à CPUs
April 12, 2010 6:43:55 PM

Probably it fried your PSU not your mobo. Borrow a GOOD PSU (what do you have now?) and go again.
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April 12, 2010 7:33:28 PM

mosox said:
Probably it fried your PSU not your mobo. Borrow a GOOD PSU (what do you have now?) and go again.


My gaming PC (the broken one) uses a 650 watt Antec Earthwatts psu. My HTPC uses a 550 watt Rosewill PSU (currently typing on it).

I know its a long post to read through but somewhere in there I mention that I borrowed the Power supply out of my HTPC and tried it with the same result. I put the rosewill psu back into the HTPC which is what I am using right now so I know its fine.

The only things I haven't tried are:

-Different DDR2 ram sticks (i only have my 2 OCZ sticks and the HTPC i have is old and uses DDR400).

-Trying the 2 CPUs in a different mobo. i dont have another AM2/AM2+ board or know anyone that has one that I can borrow and I'm also afraid to risk putting this phenom into anyone else's board anyway for fear it might brick their board as well.


:( 
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a b à CPUs
April 12, 2010 8:21:29 PM

Im going with bad motherboard. Does it give you the post "beep" when you power it up?


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a b à CPUs
April 12, 2010 8:22:47 PM

Did you reapply thermal compound when you put the heat sink back on? If not the chips could be heating up very fast causing the system to crashing. I’m sorry if this sounds simple but every so often people over look this and it can cause issues.

I would also check all of the pins on the phenom to see if any of them are bent.

If I can think of anything else later I will repost.
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April 12, 2010 9:16:31 PM

Did you use an ESD wrist strap os otherwise made sure you were grounded when making the switch?

I know it is not a problem that is too common, but you might just have been very unlucky and fried something.
I actually did that once ages ago when upgrading from a P133 to a P166. It was working at first, but then for some reason I removed the CPU again and when I reseated it....dead.
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