700mhz wall on HD4850 is smashed.

[ghost101]

Ive done the pencil mod on my 4850 but over 1.35v im getting random reboots when running Fur bench even as low as 700 on the core. im running a 850w Silverstone Zeus, do you think this extra voltage is pulling too much ? i dont want to buy another psu and find its the same. could it be a setting on my maxumus formual mobo ?


btw cards are water cooled, never going above 45c and i have heatsink on the VRM's and according to GPU-z the dont go over 45c with a fan blowing on them.

I think its possible that the 150w supply via the pci-e slot and pci-e 6pin isnt enough. 150w for all pci-e 1.1 boards. I think pci-e 2.0 boards can supply 150w via the slot and so theres 225w available.

Think about it this way, at 1.35v compared to stock of 1.15v, the power consumptiion has increased 38% before any clock increase. At 1.4v this is 48%. Say you hit 800mhz for the core, thats a combined increase of 76% and 89% respectively.

At a peak wattage of 109w



and if we attribute 80% of that to the core. A 76% increase in core power consumption is an increase of 66w. This is a peak wattage of 175w. For the 2nd scenario it would be even higher.

NB the 80% attributation to the core is a pure guess. Also, if the card xbitlabs used has a lower than 1.15v stock voltage, it would be even higher.