PC won’t start.

[Bryan]

I have a problem with a Gigabyte B460M D3H motherboard. The system has been working perfectly until I made two changes. I replaced the Intel Celeron G5905 CPU with an Intel i7 10700 CPU and added 16G G.Skill memory to the existing Corsair 16G to give 32G.
I then reattached all cables and fired it up. All fans and MB lights come on but there is no signal to the monitor. I have replaced the PSU, same result. I have connected another PC to the HDMI cable and there is a signal to the monitor. So, there is a fundamental problem.
I removed the CPU and I have found that the pins on the MB CPU receiver (don’t know what else to call it) has a little blemish towards the back of the receiver and I cannot tell if this damage to the pins. I have been very careful in removing and installing the PCUs and I cannot believe that I might have damaged anything.
I have removed the memory sticks, tried each one at a time and in combinations without change to the problem.
I’m at a loss as to what has gone wrong. Any ideas please?

[king1]

first thing to do is put everything back as it was when working, old cpu old ram old psu. Get a definitive "something is now broken" or "one of the new components caused the problem"

EDIT: At the same time you should generally troubleshoot one at a time so if you confirm it works ok with the old hardware then swap out either the CPU OR add in the new RAM, one or the other could be the problem. Mismatched RAM can be incompatible...

[king1]

looking at the cpu support list suggests you *don't* need a bios upgrade

[Wainuitech]

What happens if you put it back to its original configuration ( CPU and Memory) ?

Where you say it has a little Blemish can you get a clear picture and post it here ?

One other thing, you say the CPU is 10700 Which is fine, Does it have any other letter behind it eg. 10700K ??

Actually another thing -- Does it have a Graphic card installed ??

[Bryan]

I have put it back as it was - no change. There is no letter after the 10700. And no, there is no GPU attached. 
It now has the Celeron G5907 CPU and original 2x8 Gb Corsair memory. As for a photo, I will try but I think uploading might be a problem for me.

In trying to start, the system surges on and off in a continuous loop and no change to the message on the monitor that there is no signal.

[Wainuitech]

A power issue usually causes surges. The cause is normally a Faulty Power Supply, a damaged power Cord, or, in the worst case, damage to the motherboard.

Make sure all connections are firm, especially checking the Power to the main Motherboard and CPU power plug.

Try removing the CMOS battery for a while say 10 minutes, and put it back, see what happens.

[nzoomed]

I second that on removing the CMOS battery.
I put a metal object across the battery terminals to drain the residual power in the motherboard, make sure you do this with the power disconnected.
In theory, everything should still work if you restore the original hardware configuration unless one of the new components you swapped out damaged the motherboard.
If you can find another power supply, it would be a good thing to swap out and test with to rule that out. An i7 will used far more power than the celeron ever would and perhaps the extra load was enough to tip a failing power supply over the edge.

[Bryan]

I have tried a 2nd PSU and made sure of good connections. I did remove the CMOS battery for a minute and replaced it with a new one. While the battery was out, I did press and hold the Start button to bleed the residue power in the PC. I will do it again and leave it for a while. I do suspect a MB problem and will probably take the expensive way out. I have my eye on an Asus Prime Z590M-Plus to be able to use the i7 10700 CPU.

[Bryan]

OK, update. I have used a known to be good PSU from another PC "donner" and swapped the suspect PSU to the donner. The "new" PSU does not start the suspect PC although there is no surging. The PSU from the suspect I have installed in the "donner" and it starts that PC with no problem - that therefore would appear to rule out a faulty PSU.

[Wainuitech]

Just a thought -- How much heatsink paste was applied when the New CPU was put in, AND did you check all the pins on the CPU Socket, only takes one to be out of alignment and nothing works.

[Bryan]

Yes, I did apply sufficient paste. In my first post I did mention that I had noticed a slight blemish in the pins, all have a very slight grey colour but there is a very small area that is shiny. I have no idea how that happened as I am sure I was very careful in removing and installing the CPUs. I feel sure now that this might be my problem.

[Wainuitech]

Just regarding the paste, I was actually thinking the other way, applying too much. Seen it happen where people apply it like jam on toast and thats to much.

The other thing you can test -- Remove the motherboard from the case, on a table/bench plug in only the PSU, Keyboard /Mouse and monitor, the only components on the motherboard should be the CPU/Fan(heatsink) and 1 stick of Memory, using a screwdriver short the power pins to boot the board.

If it fires up and displays the BIOS ( or anything apart from no signal) then its either some other component or the case is shorting the board.
If it does get this far pull the power to turn it off and reconnect HDD, try again, if that works reassemble only the board (no HDD) only the power wires - try each time until it fails again.

If its still not booting, generally boards are damaged ( considering you have tested the PSU and Memory)

Just yesterday had one of my workshop PC's go a bit weird wouldn't get past the BIOS at 1st, then wouldn't boot at all -- SSD Drive was the cause

[Bryan]

Thank you WT. I have stripped the MB to CPU, 8GB Ram, kb & mouse. I had replaced the CMOS battery. Lo and behold I was able to bot into to BIOS. I had removed the M.2 SSD. I accepted the CMOS changes, saved, closed and restored the M.2 SSD. Tried to fire up and got the original fault. Removed the M.2 and installed a Win10 SSD, same fault appears.

What would my next step be please?

[Bryan]

Got it. Rebooted with the M.2 and I am back in. just need to add the i7 10700. Thanks so much!

[Bryan]

It would seem that I may have damaged 3 Ram rails. B! is the only one that recognises a RAM stick. I have a G.Skill 8GB that works, the other rails don't work.

[king1]

It would seem that I may have damaged 3 Ram rails. B! is the only one that recognises a RAM stick. I have a G.Skill 8GB that works, the other rails don't work.

cant imagine how you might have done that?  does the G.Skill 8GB that works, work in any other rails?

[Dugimodo]

Could still be bent pins in the CPU socket, the memory controller is in the CPU these days. Does your smartphone have a light and a zoom function? mine magnifies small stuff like that pretty well and lets me have a good look.

[Bryan]

Thanks for the thoughts. I will leave things as they are at present. The PC is used by my wife for surfing the Web so 8GB of RAM will be plenty. Thank you all.

[Agent_24]

I'd guess bent socket pins or misaligned CPU.