From this it looks like a good memory overclock is going to go a long way on the 68 towards improving performance.Īs for how much of an overclock is necessary, this depends on the game. Based on all the data we have, Barts looks to be memory bandwidth starved in around half the games we use. Even at the “mere” speed of 850/1150, it’s faster than the 6870 in 3 out of our 5 games and the 6870 still has a core clockspeed advantage and more SIMDs! The advantage for our overclocked 6850s is that the memory clock of 1150MHz (4.6GHz effective) is faster than the 6870’s memory clock of 1050Mhz (4.2GHz effective), and this looks to be the reason for the difference. Something that caught us completely off-guard in our results is just how well the overclocked 6850 did. As a result the controller reaches its limit before we can even push the 5GHz GDDR5 to spec. The limit we believe lies solely with the memory controller, which was a conscientious decision by AMD to trade memory clocks for a smaller die. However 1150MHz didn’t trigger performance degradation due to error correction-induced retransmission, so it looks to be a safe frequency for all cards. On a higher-end card where performance is the only attribute that matters this wouldn’t really matter, but we would not consider this a useful tradeoff on a petite card like the 6850.Īs for memory overclocking, we hit at solid wall at 1150MHz as none of our cards could do 1200MHz without artifacting. The Asus and MSI cards jumped in power consumption, temperature, and noise by around 20W, 3C, and 2dB each, for a performance difference of under 2%. While it’s possible to hit 960MHz with enough voltage, in practice it’s not worth the effort. This culminated at 1.22v on the Asus and MSI cards for 960MHzīased on these results we went ahead and benchmarked the Asus card at 850/1150, 940/1150, and 960/1150 to showcase the performance at these overclocks, while capturing data for all of the cards at 1.172v, and the Asus and MSI cards at 1.22v. We had to give the cards significantly more voltage to get above 940MHz. The 6850’s power efficiency pretty much has to go out the window here, but in return we can capture some significant performance gains.Īll of the cards could hit 850MHz core at stock voltageĪll of the cards could hit 940MHz core at 1.172v, the 6870 load voltage As a lower clocked Barts card, 6850 cards not binned for poor maximum clocks should have a fair bit of overclocking room as AMD intended for the design to hit 900MHz+. Half of our results focus on our 6850s at their stock clocks, but the other half of our results focus on the card when it comes to overclocking.
Overclocking: Performance, Power, Temperature, & Noise