Quote Originally Posted by Jimbo Mahoney View Post
I have a Sapphire 5830 that I hardmodded (vGPU only) but the core runs out of steam unusually quickly and more voltage doesn't help.

My fear is that it's simply hitting a wall and there's nothing I can do about it, but I want to explore the other possibilities (e.g. OCP, VR cooling etc.) Here's the details:

On stock voltage (~1.15V) and cooling, the core can do 1030Mhz.

vGPU mod (~1.25V) and watercooling (core only, 38'C full load), it rapidly hits a wall at around 1150Mhz (i.e. system locks up / screen goes blank).

I've taken the voltage to 1.35V with no improvement.

Having checked the 58xx overclocking thread, it does seem that most 5850s and 5870s also crap out at about 1100Mhz until using very high voltages and extreme (sub-ambient) cooling, reinforcing my feeling that this is a chip limitation as opposed to cooling / OCP issue.

Any thoughts?

In addition, has anyone found any improvement from vMem mod and/or memory cooling? (I can't find any info on this yet - still looking).

Thanks.
*sounds like voltage stability..

Use GPU-Z to monitor vDDCI and OCP% when running a graphics stress test like furmark.. chances are with such a fast core speed, you are max on input capacitance and causing voltage to drop too low on load. I noticed the same thing on my 5770, and had to add 16v caps to keep the input from dipping below 11.9v on load. Now I can run 1105mhz stable for daily gaming and bench at 1120mhz.



@ EvoCarlos- vapo chill heater..nice..and yeah, almost the same thing.