Tahiti LE Strange Behaviour
Hi all, first post here
Anyway got the VTX3D 7870 Black for myself recently and must say I am very impressed but also a bit mystified by it. I have mine fitted with an Arctic Cooling Accellero Mono Plus + cooler. For anyone wondering the mounting holes on this card are the same as a 7850/7870 despite it being a Tahiti GPU. Here is my situation and I hope this might help explain the poor overclock scaling.
My card overclocks to 1165 without any artifacts in OCCT after 3 hours- I don't see any point in overclocking the memory on these as there is already sufficient bandwith- great right? But here is the thing, when I benchmark the card in Tomb Raider and 3DMark13 im getting LOWER scores then running the card @ stock speed!! Also the core temps are 10 degrees higher at stock speeds when Benchmarking. So what the hell is going on here? So I throttled back the clock to 1050 and same problem!! All the above was done with the power slider set at +20% . Its as if the card is shutting down shaders when overclocked because it cannot get enough power to run all of them.
So please if you have this card and you have overclocked it verify that your ovrclock is actually giving you higher frame rates. Unfortunately I still haven't found an app that can change the core voltage on this card so Overclocking is out of the question at the moment- great card at stock speed though.
One more issue I have found- with the latest ATI 13.3 Beta driver the card suffers from the Clock Drop seen on other Tahiti LE Cards. Even with the power slider set to +20% the card will slow down to 500MHZ on the core after gaming for a whilen