Quote Originally Posted by jason4207 View Post
It was the memory controller on the 8800GT/GTS w/ Qimonda that didn't like additional voltage. It wasn't the memory itself. The memory and memory controller shared the same voltage line...that was the problem.

I'm not sure if the 4850 is set up the same way, though. Hopefully, it'll respond nicely to some extra juice!
Quote Originally Posted by [XC] gomeler View Post
Odd, my 8800GT with Samsung GDDR3 modules responds rather nicely, always thought it was the Qimonda modules crapping out. I'd also like to know if the RV770 power circuit has the same 1.7v OVP and if there is a sensitive OCP circuit in place? Anyone know if RV770 coldbugs badly also? All questions I could answer in a week but I'm impatient.
You are correct about the Samsung chips. My GTS w/ Samsung loves voltage. It was theorized that it wasn't the Qimonda chips themselves, but the memory controller that was causing issues on the cards that had Qimonda memory. The reasoning being that turning down the voltage actually helped one obtain higher clocks, and at the brink of stability the timings on the Qimonda chips could still be tightened w/o having any adverse effect on stability. It seemed as though something else must be at fault. The memory controller was spec'd at 1.8v, but going from 1.2ns to 1.0ns Qimonda RAM only involved pumping up the voltage from 1.8v to 2.0v on the RAM (the controller had to come along for the ride since they shared the same rail). The Qimonda RAM did fine w/ the extra voltage, but the controller wasn't stable anymore. Iirc the spec sheet on the Qimonda has them rated up to 2.5v!

Hopefully, the Qimonda RAM on the 4850 will respond well to extra voltage.