I need some help with Memtest errors

[Andy_pandy]

I tested my Ram for on several times and sometimes I get no errors sometimes I do.

first I tested my memory for 1 hour and I got no errors. second time I got 8 errors in 9min. The third time, I tested it for 20 min and got no errors.

I have attached an image to this post, showing the error.

what does it mean?

 

[Andy_pandy]

Im using mix match memory. In total I have 12GB of memory.
2X4GB = 8GB Corsair XMS Memory kit for dual channel systems, 1333MHz ,
2X2GB= 4GB Kingston DDR3 1333MHz i5 Memory Kit CL9


Motherboard: ASUS M5A97 R2.0

Default (stock) voltage



I just ran Memtest for another 40min and no errors...