I had asked about your fans in an earlier post.  This can occur due to a heat issue, as well as other issues.  Again, how many fans are you running, and are they all actually working?
 
Are fans running at max speed, or variable?
 
Reboot your computer after it has been on for a while, and look at reported temperatures and voltages in the BIOS, and post those temps and voltages here.
 
If your system has on-board graphics, it might also be worth just running a test to see if these errors come up when you use your on-board graphics instead of an added card.  (for the test you would also want to remove the card, then put the card back in after completing the test.  The video software would not need to be installed again after testing).
 
Bob Bone
 
 

So that was the sleep mode going on...which I mentioned...Thank Hector it was that, I was getting worried.
Thanks Bob.

Are your CPU cores set to run at maximum (100%)?  If not, they should be.  This can be set in Advanced Power Options.
 
Bob Bone
 
 

Well Let me count em...there are a lot.. 2x 120mms infront, one 120 on top, and one big one on the side, and then the cpu fan is working well, and then there is the power suppy one which is also working well...So if I count right that is 6 all together...for a very very chilled interior....is that a problem?...just goosing you Bob...wink.

Yes all cores active and at full tilt...no overclocking is ever done on my systems in my house..

If you now have sleep turned off, let things run for a bit and see if these errors continue to occur.
 
Bob Bone
 

not seeing it in advanced power Bob...cpu core usage is set in bois I think...?

Yes I re tweak that mess (sorry AlexS) and saved both basic and performance...one thing I do not touch is pci link state which has a power savings mode set to off in basic, but in performance it is set to maximum...should I tweak that?

Sir Les
not seeing it in advanced power Bob...cpu core usage is set in bois I think...?

The settings are in Advanced, expand the Processor Power Management settings, and you will see:
 
Minimum processor state - set this to 100%
Maximum processor state - make sure this is also at 100%
 
The above will keep your CPU running at maximum speed.
 
Bob Bone
 

System cooling policy.."active"....is what I see when I expand the power management, in power management advanced...Sorry Bob...I may need to go to a different place to get that. looked at...???