Is my CPU fried, or just my motherboard?

Apr 22, 2018
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Gigabyte board model: GIGABYTE GA-AB350M-DS3H
CPU model: AMD Ryzen 2200G
RAM: Corsair Vengeance 3200Mhz DDR4

The story (TL;DR at the bottom):

I was helping my 10 year old nephew build a computer, he's been very excited about electronics and robotics class at his school, and I've built many PC's in the past and thought he'd enjoy having someone take the time to help him learn (my unknowledgeable father was going to buy him a crappy $400 laptop, and i wanted to do better than that).
Well, things ended up going south.

Halfway through the build, I had to leave so my sister and her husband could have dinner (they have 3 other much younger kids than my nephew). Took *all* the parts and boxes with me, and the power cable for the computer (still had the bread tie thing holding it together, straight from the factory). When I went to take the unfinished PC with me, my (well intentioned) brother-in-law assured me i didn't need to take the computer, and since I told him and my nephew 3 times (each) not to even try to turn it on or do *anything* (because it's not finished, obviously), and I finally just figured I'd be good, that my nephews Dad would take care of things. Wrong (sad! jk)

My nephew took the computer into his room, set up his desk, and found a *random* cord (at least it was a 3-prong cord) in the house that would plug in, and he excitedly turned this half-built computer on. He then realized I hadn't plugged power into the motherboard yet (smart kid, too smart), so *he* (10 year old) ended up putting power from the PSU into the SYS_FAN1 socket, and when he powered it up to charge his phone (ghaaaaaaaaaaahhh whyyyy) it kept turning off, and he kept turning it on, for hours.

What I'm wondering now... Is the Ryzen 2200G and the 3200Mhz DDR4 RAM going to be functional when i replace the board? Or should I assume they're fried too, so i can buy them ahead of time and install them *if* the current ones are fried (and return them if not)?

I'd like to order the parts I need from Amazon (again), and return the board my nephew accidentally busted and do it through the warranty process, so he can get his computer working right and not feel bad for 1-2 months? My nephew is a good kid but he's devastated that he did this, and the worst part is his Dad/my brother-in-law yelled at him for it, even though i assured him it's ok (they're not paying for this either, I am...)

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TL;DR: 10yo Nephew (when I wasn't there) plugged power into a half built PC by plugging the PSU *directly* into SYS_FAN1 on board with CPU and RAM plugged in (no GPU), while the board was also getting power from PSU normally. When PC kept turning itself off because he was charging a phone, he kept turning it back on. For hours....

Replace just the board, or replace board, cpu and ram? Specs for PC at top of post.
 
Solution
the other parts should be fine. once the 12v melted the fan controller chip and made a dead short most power suplys/mb wont turn on. for the mb you can do what most 10 year old do when they short out a mb they do a no post rma and get a new mb back from amazon. if you want to try the mb vendor ask for customer relation and ask for a one time warranty exchange. when i worked for micro center had a apple desktop come in a few days after xmass with a non working dvd drive. there kids jamed a pb and fluff sandwich into the drive. the whole drive was bound up by the fluff. apple gave the family a one time repair on the dvd drive.
Apr 22, 2018
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Corsair CX Series 550 Watt 80 Plus Bronze Certified Modular Power Supply (CP-9020102-NA)

Man that would be great if it would be ok, but everything is correctly hooked up and I can't get the board to do jack all.

The one thing other than motherboard failure I am thinking is a possibility and have not been able to confirm, is if somehow the case buttons are not hooked up properly and the power button isn't working, but my nephew already proved to me that they were when he kept turning the power on when he was alone. You think maybe it's the PSU?

Edit: called Corsair, they said to try paperclip test, I'll update you guys in what happens. First i had to find a metal paperclip, rofl.
 

1.Corsair CX550M is a good quality power supply. It has over-voltage and under-voltage protection, over-power protection, and short circuit protection built in.

2. If there was any damage to the motherboard you would likely see and/or smell it. Do you see any burn marks, melted plastic or notice a burnt/smoky smell anywhere on the motherboard?

3. When you say the board won't do jack all, what exactly is happening when you boot?
 
Apr 22, 2018
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Well i guess it is the board after all. Paperclip method boots the power supply with nothing connected, and now that i examined the board under better lighting conditions, i see that trademark grey dusty looking "burnt" look on the back of the board where my nephew plugged the PSU into...

So now how do i determine if the CPU and RAM is OK? I want to put the CPU into a new board, and am pretty sure it wouldn't hurt a new board if I tried to test it.... Right? What about the RAM? If it was an Intel CPU i would throw it into my computer tonight and test, but this is an AMD CPU so that's outta the question.
 

Sorry to hear that. With the CPU and RAM just do a visual inspection like you did with the motherboard. If they were bad, they would not harm another motherboard, they would just not work. If you are buying your parts at a local computer store, they could do a quick test of all your parts to make sure they are working.
 
the other parts should be fine. once the 12v melted the fan controller chip and made a dead short most power suplys/mb wont turn on. for the mb you can do what most 10 year old do when they short out a mb they do a no post rma and get a new mb back from amazon. if you want to try the mb vendor ask for customer relation and ask for a one time warranty exchange. when i worked for micro center had a apple desktop come in a few days after xmass with a non working dvd drive. there kids jamed a pb and fluff sandwich into the drive. the whole drive was bound up by the fluff. apple gave the family a one time repair on the dvd drive.
 
Solution
Apr 22, 2018
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Thank you so much Rocktalkrock and Smorizo!

I called Gigabyte now that they were open for calling on the phones today, they told me to call Amazon where I ordered the board. And today was the last day (!!) to do Refunds and Exchanges through Amazon (even though their site said it ended yesterday lol)! If I'd bought it through Gigabyte through Amazon directly I could have done the exchange right then, but the vendor I got it through was a Prime vendor so it worked out.

Got the credits in my Amazon account before the 15 minute call was over, got a new board ordered as soon as the call ended. Hopefully the CPU amd RAM is good, my nephew will thank you, if they don't then I'll have to sit him down and tell him that's why you don't assume you know everything when it comes to electronics, costs you more time than it saves!

Thank you!