strange CPU utilization throttling with OCCT - help!

Just purchased a Q9550 and Gigabyte P45-UD3L board last night. Got it installed with an OCZ Vendetta 2 cooler and Scythe 1900RPM 120MM fan. Vista 64 SP1, drivers from Gigabyte CD installed. Running OCCT Linpack 64-bit stress test the temp gets up to 69/70 degrees on the 1st core (low-mid 60's on the other 3) and then all of a sudden the CPU utilization will drop to 25%.

Running BIOS rev. F4. I've disabled EIST, thermal monitoring, C1E, all temp and fan warnings in the BIOS. What could be causing this? Either I'm missing something in the BIOS or the stupid Gigabyte DES software (which I accidentally installed with the "auto" option from the CD) is doing this, despite having already been uninstalled.

Help please!

Update:

I have determined the trigger for the problem is indeed temperature, as I suspected. Running Intel Burn Test or OCCT Linpack quickly causes the 1st core to reach 70 degrees C at which point the test throttles down to 1 thread. Running Prime 95 only causes the temp on Core 1 to reach 60 degrees C and there is no reduction in CPU utilization.

Any thoughts?

That's how the Linpack test is designed. It goes full 100% load and then between each round it drops down to 25%.

Prime 95 Small FFTs will keep the cores at a steady 100% but usually doesn't create as much heat as Linpack testing does.

Your computer is nowhere near thermal throttling so no worries. That doesn't happen until the cores approach 100C. Usually 97C or 98C on most 45nm Core 2 Duo or Quad CPUs.

more memory makes the linpak test run longer before it takes a rest to do the next iteration.

That's good to know, thanks guys.