Large temp differences between X2 cores

[BlueWeasel]

DFI NF4 Ultra-D
X2 3800 @ 2.56Ghz (256x10) with 1.40v
Scythe Ninja with stock 120mm fan
Intake fans: 80mm, 120mm
Exhaust fans: 120mm, PSU (80mm)
CM Centurion5 case

CoreTemp reading with ORTHOS running

I've always wondered why I noticed such a large difference between Core 0 and Core 1 when using CT. Could it be a fluke reading or considered normal?

If it's accurate, then it would seem I'm not getting contact with the Ninja base directly above Core 1. I've seen that others with this problem have solved it by removing a very concave IHS. It's not something I really want to do, but could it be the cause?

 

[fluffmonster]

same thing happens to me. thought maybe the heatsink wasn't on quite right, but tis only a guess. would love to hear a surer answer.