You've had two memtest86+ failures, is the second one from a new ISO file?
The last memtest86+ picture shows a mostly blank screen, was the whole test like that?
It should have looked something like the picture below, there will be no info with a Red background unless you get errors, should look like the section with the blue background if there are no errors.
View attachment 216984
Normally any errors or if it stops on it's own means a failure, it is possible that the ISO is corrupt or wasn't burned to CD, loaded on memory stick, correctly.
Your computer manual isn't very clear, do you have any/many settings to adjust in your BIOS?
RAM or CPU, frequency, voltage, or anything similar?
Any RAM timings adjusting section?
Most OEM computers do not have anything above basic settings, your manual talks about 'sliders', can you clarify what controls are available to you?
Follow the video Greg posted and remove two RAM cards, check your motherboard manual to see which RAM slots should be used, check if you have any crashes.
If you have any crashes or not, run memtest86+ as per the tutorial linked previously.
D/L CPUZ and post a snip of the CPU, Mainboard, Memory, and SPD tabs.
For posting the information , enter 'Snipping tool' in the Start button > Search box, hit enter. Select the area you want to post and save to a convenient place.
How to Post a Screenshot in Seven Forums
Have you been checking your temperatures?
Use Core Temp, to check the CPU temps when at idle, under load and/or testing.
Let us know the minimum and maximum temps you get.