Sorry if i seem somewhat ignorant or oblivious to what you are saying , I do get everything you have said and really appreciate the time you're taking to offer advice.
I get best option is to just get a new psu, just trying to cover as many possibilities before having to spend money atm.
It's just frustrating that as long as the pc is actively doing a task, it is running fine as soon as you come of load it is freezing......I'm guessing a faulty psu would not effect the system when running in bios as no load variance....
Given the models of PSU involved, and the fact that lower quality or older platforms might generally not support some of the newer power state requirements, or that units might go out of spec under low load conditions, it could still absolutely be a PSU related problem. In fact, in some cases it might be more common than having problems due to the other end of the spectrum with full load issues.
Again, it might well NOT be PSU related, but it's impossible to know without having something you are certain is decent quality and reliable in there, and neither of the units you have fit that description IMO.
I think your best bet is to get a reliable, good quality power supply that's at least 550-650w so that it will without question be enough for that GTX 970 (Which yes, I understand you've removed it and still had this problem. Even so, if you buy a new one you want it to be capable enough that you CAN put the graphics card back in) and then use the information at the link I gave you earlier in order to bench test your hardware. It should get you in the ballpark at least.
Once you have a reliable PSU it would probably be a good idea to run Memtest86 as well, to eliminate the memory as the source of the problem.
Memtest86
Go to the Passmark software website and download the USB Memtest86 free version. You can do the optical disk version too if for some reason you cannot use a bootable USB flash drive.
Create bootable media using the downloaded Memtest86. Once you have done that, go into your BIOS and configure the system to boot to the USB drive that contains the Memtest86 USB media or the optical drive if using that option.
You CAN use Memtest86+, as they've recently updated the program after MANY years of no updates, but for the purpose of this guide I recommend using the Passmark version as this is a tried and true utility while I've not had the opportunity to investigate the reliability of the latest 86+ release as compared to Memtest86. Possibly, consider using Memtest86+ as simply a secondary test to Memtest86, much as Windows memory diagnostic utility and Prime95 Blend or custom modes can be used for a second opinion utility.
Create a bootable USB Flash drive:
1. Download the Windows MemTest86 USB image.
2. Right click on the downloaded file and select the "Extract to Here" option. This places the USB image and imaging tool into the current folder.
3. Run the included imageUSB tool, it should already have the image file selected and you just need to choose which connected USB drive to turn into a bootable drive. Note that this will erase all data on the drive.
No memory should ever fail to pass Memtest86 when it is at the default configuration that the system sets it at when you start out or do a clear CMOS by removing the CMOS battery for five minutes.
Best method for testing memory is to first run four passes of Memtest86, all 11 tests, WITH the memory at the default configuration. This should be done BEFORE setting the memory to the XMP profile settings. The paid version has 13 tests but the free version only has tests 1-10 and test 13. So run full passes of all 11 tests. Be sure to download the latest version of Memtest86. Memtest86+ has not been updated in MANY years. It is NO-WISE as good as regular Memtest86 from Passmark software.
If there are ANY errors, at all, then the memory configuration is not stable. Bumping the DRAM voltage up slightly may resolve that OR you may need to make adjustments to the primary timings. There are very few secondary or tertiary timings that should be altered. I can tell you about those if you are trying to tighten your memory timings.
If you cannot pass Memtest86 with the memory at the XMP configuration settings then I would recommend restoring the memory to the default JEDEC SPD of 1333/2133mhz (Depending on your platform and memory type) with everything left on the auto/default configuration and running Memtest86 over again. If it completes the four full passes without error you can try again with the XMP settings but first try bumping the DRAM voltage up once again by whatever small increment the motherboard will allow you to increase it by. If it passes, great, move on to the Prime95 testing.
If it still fails, try once again bumping the voltage if you are still within the maximum allowable voltage for your memory type and test again. If it still fails, you are likely going to need more advanced help with configuring your primary timings and should return the memory to the default configuration until you can sort it out.
If the memory will not pass Memtest86 for four passes when it IS at the stock default non-XMP configuration, even after a minor bump in voltage, then there is likely something physically wrong with one or more of the memory modules and I'd recommend running Memtest on each individual module, separately, to determine which module is causing the issue. If you find a single module that is faulty you should contact the seller or the memory manufacturer and have them replace the memory as a SET. Memory comes matched for a reason as I made clear earlier and if you let them replace only one module rather than the entire set you are back to using unmatched memory which is an open door for problems with incompatible memory.
Be aware that you SHOULD run Memtest86 to test the memory at the default, non-XMP, non-custom profile settings BEFORE ever making any changes to the memory configuration so that you will know if the problem is a setting or is a physical problem with the memory.