Yes, your description gives a fair possibility of a hardware level issue, which may be the motherboard itself. I see you are suspecting a capacitor on the board. Is it visually bad? If so, your decision is totally right.
Otherwise, as you want to do some troubleshooting before getting a new board, IMHO it would be a good choice. Do some troubleshooting steps, at both the hardware level and the software level.
At the hardware level, test all the possible hardware components, thoroughly.
Hardware test Step 1: Stress testing:
1. Test your RAM modules for possible errors.
Run memtest86+ for at least 8 consecutive passes
If it start showing errors/red lines, stop testing. A single error is enough to determine that something is going bad there.
Take a camera snap of the memtest86+ window before closing the program. Let us see it.
Screenshots and Files - Upload and Post in Ten Forums - Windows 10 Forums
Stress test the Graphics Card/s using Furmark.
Take a screenshot
of the furmark window before closing it. Upload the screenshot
for us. Also let us know if you have experienced any crash/BSOD and/or artifacts during the test.
If possible, disable SLI and test the cards individually, too.
Stress test the CPU.
Hardware test Step 2: Elimination testing:
1. Set all the hardware elements like RAM, CPU and graphics card at their base clock. Eleminate all possibilities of an overclocking; and disable XMP.
2. Your RAM KIT should have four sticks. Remove all but one. Let the computer run for a reasonable time with only 4 GB RAM. See how it goes.
3. Remove the Graphics cards. Let the computer run with the processor graphics only.
4. Re-seat the SATA and power cables. If possible, apply new SATA cables, and try the disks on the unused SATA ports on the motherboard.
5. Remove all the connected devices other than the keyboard and the mouse.
Software level testing: Made easy:
- Boot into the BIOS setup. Load the Optimized BIOS defaults.
- Disconnect all the disks other than that one containing the C drive, I think the SSD.
- Perform a Clean Install of Windows 10 on it. Windows 10 - Clean Install - Windows 10 Forums
- Dont apply the Driver CD at all. IT IS A MUST. Forget about that one at this stage.
- If the installation accepts the LAN driver, good. Otherwise apply the LAN driver you previously downloaded.
- Get all the drivers via Windows update. Set it here: Device Driver Automatic Installation - Turn On or Off in Windows 10 - Windows 10 Forums and run windows update. Windows Update - Check for and Install in Windows 10 - Windows 10 Forums
- When the system is fully updated, add the necessary programs.
- ** Watch minutely, at which point the problem starts. It may have different meaning depending on the stage of occurrence. Let us know.
If the tests are individually good, but the issue occurs irrespective of everything then we can blame the motherboard.
Suggesting for all it; because if it is not a failing motherboard but something else then the issue might re-occur even after changing the board.
But, if you really plan to/need to replace the motherboard, then if your windows 10 is retail, then there is no problem; you can do it anytime.
If it is an upgrade form a previous OS, be sure to replace the motherboard before 29th July. Get the new board, install your Original OS, upgrade it to windows 10. Windows 10 - Upgrade Installation - Windows 10 Forums
This process you grant a digital entitlement to your new board, and it will be permanently activated.
7. To Upgrade to Windows 10 with an ISO file
After 29th July, you will need a Retail Windows 10 license to activate windows 10 on a new board.