Question

Monitors with no signal from computer.

The problem at first was that the Ryzen 7 3700x I bought was, in fact, compatible with my motherboard, but the motherboard needed a bios update.I went to a friends house, borrowed their CPU, then updated the bios. I put my own CPU back in and after one failed attempt of turning it on, it worked. I was able to boot up the BIOS. What was that failed attempt you ask? Well the CPU cooler started, then stopped, started again, and then stopped--repeat. The weird thing was that it did it in sync with the fan mounted in the front of the case. Mind you all of the other fans were still working. I re-slotted the RAM after that first attempt, and that was when it worked and ran normally. I drive all the way home, thinking the problem was fixed, hook the computer up to my system, and then the same problem occurs... well half the time. Sometimes the CPU cooler starts and stops with the front fan as mentioned before, but sometimes it just stops at the beginning for a few seconds, then runs continuously. Looking at it closer, the GPU fan isn't working either, which is weird because it was working the very first time I turned it on. The DRAM_CPU LED on the motherboard remains on when the system is running as well. I looked into this extensively thinking it was the problem, but after seeing it boot at my friends house, I wasn't convinced. There isn't a problem in the vrm section, I reset the BIOS-and now updated them, tried different ram, and I reset the CMOS. Any help is greatly appreciated.

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Comments
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Answer
Time to ask the motherboard maker.

There are a lot of boards with issues but here you left out that detail so my advice is to ask the motherboard maker what's up.

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It's an ROG b450-f gaming motherboard.

PC part picker says that it is incompatible with my cpu unless I update the bios of the motherboard... which I did. I'm buying a new psu today because I'm thinking that there's a short. Especially because of all of the weird fan and boot behavior.

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Why is the PSU suspect?

Also share with the forum what the motherboard maker told you.

A short would not do what you noted. A short would cause the machine to shutdown. PSUs today have short detection circuits so the CPU fan behavior would not have me think "short." It would have me go over the machine and build the minimum parts on cardboard. I find new builders bolt it all in the case in a rush.

Other things I see a lot of:
1. Reuse of very old parts (PSU, what else? your posts are missing detail.)
2. Case reuse and forget to remove old mounting posts.
3. Not calling, messaging the board maker.

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What I've done

I was originally blaming the psu because the weird behavior was not only with the cpu, but with the graphics cards and case fans. A lot of the symptoms I've been having point to a psu problem-as the internet told me. I bought the new psu and nothing has changed, like you said. I will message the board maker and follow up with you. The only parts from my last system that are in this build is my gamingx 1070, wifi card, and drives. Here's my build (the case is wrong. It's a full size)- https://pcpartpicker.com/list/66Fyvn

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The list looks fine.

What happens with the minimum build on cardboard? We only need the PSU, motherboard, CPU and one stick RAM. That's just to do a power up test. If that fails the problem is in those parts.

After that success I try a GPU and if that works it goes in the case.

New builders skip this process and head to a full build.

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I think it's the mobo.

I've been doing this. I know it's not a problem with the graphics card. Remember it did successfully boot once. I'm thinking it's either a faulty motherboard, or a problem with the bios. Someone told me that I needed to update the AMD chipset driver before updating the bios.

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Odd.

For the minimum build there is no HDD, ODD, SSD or other drives. So I can't see how that could hold true (have to update drivers.)

If you can't get the minimum build working on cardboard the suspect parts are there, not drivers since there is on OS or storage to hold those drivers.

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I did it..

I booted with a stick of ram, cpu, and psu on cardboard and same result. I did however notice that my usb's are working. The keyboard and mouse are lighting up. The VGA light is on. I'm trying to find solutions to this problem but I can't seem to find any.

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I was unclear.

The solution is to make it as small as possible and test for the expected results. When the smallest number of parts is not yielding the right response the part or parts in that build are defective.

The solution as many learn is to swap in good parts one by one. I've had new techs that had a hard time with this.

https://www.asus.com/us/Motherboards/ROG-STRIX-B450-F-GAMING/HelpDesk_CPU/ does point something interesting. This CPU is 105W or the highest power draw of the lot.

It's very important the motherboard be a current revision since the maker could have had issues at the higher power levels. This is where I have to defer to the motherboard maker's answer about their board. At the shop the board would have been swapped out by now.

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You may have misread.

I think you misread. The 3800x draws 105W. The 3700x only draws 65W. If I were to take this to a best buy do you think that would be a good option. I know PC builders aren't too keen on Best Buy, but they do have good prices. If not, where should I take it to explain my problem? I live in the Tulsa Oklahoma area if that helps at all.

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Should Work OK

I would check all BIOS settings. First make sure the BIOS you updated to is the correct one for that board revision. Next check speed setting for RAM. Then the multiplier if exist for the CPU setting.

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Yup.

It's a table and I went to the wrong line.

-> THINK back to when it worked. We know this board works with another CPU but not this CPU. You can try pulling the CPU out and see if it's seated right BUT if that fixes it, then the troubleshooting is still the same as always. "Make it small as possible" so you only have the bad part or parts in the mix.

Since the PSU and the motherboard worked along with other parts then why isn't the CPU or the install of the CPU the prime suspect?

-> Think about when you unpacked the CPU. Was it factory sealed? I don't like finding an opened CPU package. When we see that, we often find the unit was an RMA and dead.

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AMD CPU

I've seen that happen if there's a bent "pin" on the CPU, and therefore not installed correctly.

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It worked with my CPU.

I'm not sure that I was very clear in my op. The computer did in fact boot ONCE with the cpu I have installed right now. I took it home from my friends house (where I was using his cpu) and it hasn't booted since. I've tried on 3 separate monitors with dvi, hdmi, and display ports. The monitor does seem to recognize some sort of connection, because after I turn on the computer it switches from "No cable detected" to just a solid black screen. "No cable detected" pops back up after I turn the pc back off. After the boot process that VGA light still remains on.

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Could it be thermal paste?

I have taken the CPU out a few times to look for bends and to use my friends CPU. The thermal paste is starting to go away. Could that be what is causing this?

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Less Likely

When a CPU overheats it typically crashes the computer, completely.

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Can I try cleaning the CPU.

Is there a way that I could go about cleaning the actual pins of the cpu without harming them? Do you think this would help? I've seen people do it with a paintbrush and alcohol. The cpu is non-replaceable and non-refundable so I'm in a bit of a predicament...

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toothpick

Is what I've used between pins to help clean and straighten them again. If you have some alcohol on it and use a can of air to blow it off, maybe that will help too.

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Another way?

I've also seen people using a razor blade to straighten out the pins. It seems like it would work fine but I don't know how it will work out.

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mechanical pencil helps too

Can fit over bent pins if the pencil lead is removed and help to straighten pins. On older larger pins I've used coffee stirring sticks too.

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I don't think that it's the CPU anymore.

I wiggled the lever around with the cpu in the socket and the cpu goes in extremely smooth. Startup seems to be ok now. It' just the VGA light that's still on with no input from the monitor. The monitor seems to be recognizing the connection, but is displaying nothing but a black screen...

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Answer
So it fast booted with this CPU?

Reset the CMOS, test.
If working, stop.

Fail? Try the other reset. Remove power, press and hold the power button for 60 seconds and release. Repeat the CMOS reset, test.

The story sounds like a motherboard and CPU issue. It does NOT tell you which even if another CPU works. This can confuse your new techs but I've seen version 1.x boards fail with a certain CPU and the maker doesn't tell you unless you ask.

Again, it's something you stop working until the motherboard maker checks your board version, BIOS version and CPU step level out.

This reads exactly like a bum CPU and board combo story with the owner flailing about looking for the cure short of the calls to the maker or RMAs of board and CPU.

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Wow

Yes I've tried all of this. It did boot once with this CPU. I have contacted the manufacturer and they haven't replied yet. Also went in a live chat with them and they said to send the motherboard in for repair.

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They know something.

They usually won't tell consumers. It's a common story and why I pull the plug early and RMA. If the second board fails we change make and model.

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