PC "sleeps" randomly Is my power supply voltages o.k

Hi all, My PC is going into a "sleep" mode and its not possible to wake it or shut it down unless I press the power button for 7 seconds and a re-boot takes me to the Bios but the settings are fine so a quick "exit and dont save" gets back to windows, when the PC "sleeps" my monitor will go black and say "no input signal from Display Port" but if I was playing music or a movie I can still hear the sound, I tried another monitor but its the same problem even with HDMI or DP but before this sleep problem my GTX Titan 6GB video card got some weird lines on the screen so I thought the Titan was broken so I got an RTX 2070 8GB and thats when this sleep mode thing happened but no weird lines. I dont have the RTX 2070 anymore but I sent it back to the place I bought it from for them to test it and they said it was fine and I replaced the 2070 later with a GTX 1050 Ti 4GB but it happens with this card too so if its my power supply (AX1200i) what can I try that I have not done, I tested the power supply voltages with my multimeter and a paper clip to power it on with a 12 volt fan and a SATA 80GB HDD are the voltages for my power supply correct.

all multimeter reading are xx.xx volts

Through the 24 pin motherboard cable:

all +3.3 volt = +3.33 volts

+3.3 volts & sense = +3.33 volts

all +5 volts = +5.01 volts

+5 volts SB = +5.05 volts

all +12 volts = +12.09 volts

-12 volts = -11.89 volts

all COM = 0.00 volts

On the power supply pins for "PCIE" 8 pins per socket:

all +12 volts = +12.08 volts

all COM = 0.00 volts

On the power supply pins for "Peripheral and SATA" 6 pins per socket:

all +3.3 volts = +3.33 Volts

all +5 volts = +5.01 volts

all +12 volts = +12.08 volts

all COM = 0.00 volts

the +12 volts will fluctuate by 0.01 volts between +12.08 and +12.09 so I chose the lowest value

I have tested all the cables while connected to the power supply for proper voltage output and tested for shorts with continuity for all cable pins as they are red Cablemod cables made for my power supply but bought as a kit from a shop so not hand made by me, I have the original cables from my power supply and I checked them too to make sure the Cablemod cables are all right. The Cablemod cables dont have any markings to distinguish between PCIE and CPU cables but I have the proper 8 pin and 4 pin cables for the CPU connected.

Does the AX1200i power supply have a relay or two as I can hear a relay type of click sound at power up of the PC, I removed the power supply from the PC and used the self test button on the power supply which comes up with a green light and the fan spins.

I have tested the 240 volts power supply to the PC which is through a power board and I get AC 234.7 to 235.0 volts and in another room without a power board its 234.8 to 235.2 volts, with my PC system its never been overclocked and all PC parts were new from a shop back in 2013 that has been running smoothly till about 6 months ago its always been looked after so no bad dust levels and the PC is not sitting on carpet the only thing I have changed is I had a 64GB ram kit and I removed 32GB so now its running in dual mode and not quad mode I made sure ram placement was correct from the motherboard manual but this was months before this sleep thing.

Lastly I tested using the GTX Titan again and it had the lines for a short time and then it was fine but didnt get into Windows fully maybe because of a driver issue I didnt bother to uninstall old drivers I just wanted to know if the card was o.k or not