Furmark weird squares

[B&W]

im running furmark after overclocking my 5850 to:

core 825 mhz
memory 1190 mhz

when i run furmark im getting blotchy squares on the donut, it wasn't doing this before and i ran a 20 minute test before and it was stable, is this normal or just a furmark error in the program or something

 

[gord]

What was your 20 minute test with?

 

[Memphis]

If you are getting artifacts, you are not stable. Lower the clocks and try again.