BSOD at random, also PC locking up for 5-10 seconds. error 0x00000101

Code:

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CLOCK_WATCHDOG_TIMEOUT (101)
An expected clock interrupt was not received on a secondary processor in an
MP system within the allocated interval. This indicates that the specified
processor is hung and not processing interrupts.
Arguments:
Arg1: 0000000000000019, Clock interrupt time out interval in nominal clock ticks.
Arg2: 0000000000000000, 0.
Arg3: fffff8800396a180, The PRCB address of the hung processor.
Arg4: 0000000000000007, 0.

Let us begin with some hardware testings.

Stress test the CPU.
Hardware - Stress Test With Prime95

Test your RAM modules for possible errors.
How to Test and Diagnose RAM Issues with Memtest86+
Run memtest for at least 8 passes, preferably overnight.

Stress test the Graphics Card using Furmark.
Video Card - Stress Test with Furmark

Are you overclocking? As you are getting BSODs, you should stop overclocking and run all the hardware components like CPU, GPU and RAM to their default settings. Also set the BIOS to default, too.
How To Clear CMOS (Reset BIOS)

Is the computer hot? Report us the heat of the computer after a couple of hours of your normal usage. Upload a screenshot of the summery tab of Speccy.

Lte us know the results. Also upload your MSINFO32.nfo file.

1. Click on the start button
2. Type "msinfo32" (without quotes) in the search bar of the start menu, click the resulting link. It will open the System Information window.
3. File>Save. In the "File Name" filed, put "MSINFO32" (without Quote), give the save location to desktop, and click the "save" button.
4. Give the time for processing, it will save a .nfo file on your desktop.
5. Zip it, and upload it following the instruction.

Have you taken the memtest? What is the result?

I hope you ran memtest for 8 passes at least?

If the GPU test also comes free from errors, enable Driver Verifier to monitor the drivers.
Driver Verifier - Enable and Disable
Run Driver Verifier for 24 hours or the occurrence of the next crash, whichever is earlier.

   Information

Why Driver Verifier:
It puts a stress on the drivers, ans so it makes the unstable drivers crash. Hopefully the driver that crashes is recorded in the memory dump.

How Can we know that DV is enabled:
It will make the system bit of slow, laggy.

   Warning

Before enabling DV, make it sure that you have earlier System restore points made in your computer. You can check it easily by using CCleaner looking at Tools > System Restore.

If there is no points, make a System Restore Point manually before enabling DV.

   Tip

• If you fail to get on the Desktop because of DV, Boot into Advanced Boot Options > Safe mode. Disable DV there. Now boot normally again, and try following the instruction of enabling DV again.
• If you cannot boot in Safe mode too, do a System Restore to a point you made earlier.

Let us know the results, with the subsequent crash dumps, if any.

DannyFishcharge said:

Not sure if it has any bearing on the problem, but it seems to be more likely to happen when using the USB ports for charging my iPhone.... PSU problem??

Good point.

What is the wattage of the PSU and how old it is?

And, Disable USB Selective Suspensd too.
USB Selective Suspend - Turn On or Off