I have had this problem with the Ultra since getting it, around 8 months ago.
The Aquasuite reports a doubling of power to 10W, though the frequency is constant at 61Hz. The attached flowmeter shows 0L/h, and the cooling ability is severely limited.
The only way i can find to fix it is to suspend the computer. It is ok after resume ... until the next time.
I'm wondering if i should RMA it? It is usually a minor issue, but on one occasion the system overheated badly.
Running Vistax64_SP1 - Aquasuite 4.64.00.