Quote Originally Posted by Chickenfeed View Post
A TDP of 160 is likely the total board power not the die itself. The X2 should consume a decent amount less than 2 4870 512s. My guess would be in the 250-280 range.
The HD 3870 had a TDP of 105, then the HD 3870X2 had a TDP of 190, so you get the 20Watts i'm talking about. If you check NVIDIAs 8800GT to 9800GX2 you see the same range of optimization.

then for HD 4870 you have 300Watts or so, there is no way they can lower 70 Watts to get it to 250Watts that is already a lot of heat to disipate.