Power, Temperature, and Overclocking
AMD has put a lot of time and effort into making these new HD 7000 series chips very power efficient. Using TSMC’s latest 28 nm HKMG process, these chips should provide very good performance without breaking the power bank. As previously stated, the 7850 is a 130 watt TDP part while the 7870 is rated at 170 watts TDP. Compare this to the N580 GTX which is (mostly) 250 watts to 300 watts and the 7970 which is again in the 250 to 275 watt range.
At idle we see the zero power state kick in nicely for the AMD cards. Once things get moving though, we see the advantages of the 28 nm process. The HD 7870 was right next to the N580 GTX in performance throughout testing, but at load is a good 81 watts lower in power consumption. Less power at the wall and a lower overall temperature are good things.
On the cooling side things are a bit different. The N580 GTX features the MSI Twin Frozr III setup, while the R7970 is the updated Twin Frozr IV. These two designs are very high end and feature large fans and a massive (and tightly packed) aluminum fin array. At idle we see a pretty hefty difference in temperatures, even with the older N580 GTX. At load we again see how well those MSI units perform, even with much hotter and larger chips to cool. The HD 7850 is right there, but it is a lower clocked chip with a much lower TDP. The HD 7870 is a bit toastier, but still well below the 85C to 90C that we see reference cooling designs hit.
Overclocking
The Black Edition cards from XFX are already overclocked. In this case the HD 7850 is at 975 MHz core (up from 860 MHz stock) and the HD 7870 is 1050 MHz core (up from 1000 MHz stock). These are not terribly aggressive overclocks, though it can be argued that the 115 MHz uptick that the 7850 received is still pretty hefty.
The MSI Afterburner software did not work with these cards, so voltage modifications could not be introduced. When Afterburner was run, the entire system would lock. As such, I was forced to use the native overclocking tool provided with the AMD drivers. I set Power Tune to + 20% and went for it.
The HD 7850 had a driver limited max speed of 1050 MHz, and it hit that very easily. The top memory speed came in at 1375 MHz (5500 MHz effective). This gives a total bandwidth of 176 GB/sec. Not a bad result, and as such it provided a nice boost for the card in games and benchmarks. It was not able to match the overall performance of the XFX R7870 because of the disabled stream units, but it should be faster than a stock clocked HD 7870.
The HD 7870 was a bit more interesting. The top allowed overclock by the AMD driver is 1400 MHz. I was not able to reach that speed. Instead I was able to get to 1225 MHz stable. This is a nice 175 MHz jump from the stock clock, and in every case this card was able to outrun the older N580 GTX. I did see the temps go into the 80s though, but the fan profile kept the speed around 40% and it was certainly not annoying in terms of volume or fan whine. The memory hit the same 1375 MHz as the HD 7850 did. Anything over that caused performance to drop.
nice review but i wish there
nice review but i wish there were more benchmarks…
What else would you like to
What else would you like to see?
We need to see: Batman Arkham
We need to see: Batman Arkham City, Civilization V, Crysis 2, Metro 2033, Shogun 2, Unigine Heaven and perhaps Diablo 3 :).
isnt it more relevant to
isnt it more relevant to compare these cards to 670 / 680, then the older generation nvidia cards?
it is just that reading this is like reading a review from 4 months ago.
The Lightning R7970 results
The Lightning R7970 results are essentially dead even with a GTX 680.
What I’d like to see are
What I’d like to see are comparisons to the generic versions of these cards. You price the XFX 7850 at 275$ but is it worth the extra 45$ compared to say XFX’s generic 7850 that they sell for 240$ (free shipping)?
You defiantly hit the nail on the head with the 7870 though. As awesome looking and well performing as it is it’s priced too high.
AMD 990FX Platforms not beat
AMD 990FX Platforms not beat SandyBridge in Skyrim and Dirt 3. But My Test Dirt 3 with HD 6950 stock 1680×1050 Beat HD 7850 FPS: 65avg/57min and OC (940/1375) 75avg/64min beat HD 7870 too with 2500K + Z68 Stock!
Def needs Crysis 2, Metro
Def needs Crysis 2, Metro 2033, and UniEngine added. Also show the new 600 series results along with these, still a good review though.
Heh, I tested Metro 2033 and
Heh, I tested Metro 2033 and even graphed out the results. I just forgot to put them in! I’ll add those here shortly.
I’ll try to get a hold of a GTX 680 or 670 here soon so I can have those results available to me.
Great review Josh, thank you.
Great review Josh, thank you.
AMD has dropped the price on
AMD has dropped the price on these cards. The 7870 DD is now only $279 after rebate. That certainly changes the game, doesn’t it?