At what core frequency does a 7850 become roughly equivalent to a default 7870?

[dennilfloss]

That is a 1000MHz 7870?

Edit: At 1920x1200.

This would suggest 1050MHz (according to the preceding page) is close depending on the game.

http://www.anandtech.com/show/5625/...-7850-review-rounding-out-southern-islands/19

 

[Termie]

You basically have your answer, but there's one minor catch. That 7850 also has a memory overclock, which is affecting the results (see the advantage in Skyrim at 2560, a bandwidth hogging setting, and loss at 1920). For this reason, it's actually winning most of the matchups.

That being said, the common wisdom has always been that the 7870 has a 5% clock-for-clock advantage (which goes for many of the higher-end cards in various AMD series).

That was why the common wisdom was also that the 7850 was the better buy, since it could be overclocked to the same levels (and thus to within 5% of the performance, where it does not stand at stock speeds). The problem now is price - the 7870 has fallen so far that unless you have a power or size requirement you're trying to meet, the 7870 is the better value ($30 more for 10% more stock performance and 5% more OC'd performance).

Take, for example, the offerings at NCIX, the Canadian equivalent of Newegg:

http://ncix.com/products/index.php?minorcatid=108&subminorcatid=109

A solid aftermarket version of the 7870 (XFX Double D) is available for an amazing $215AR, whereas the cheapest 7850 (a reference model) is $180 and most are over to $200. I'd say there isn't much of a question that the 7870 is the one to buy.

 

[OVerLoRDI]

7870 has 1200 SPs @ 1ghz
7850 has 1024 SPs @ 860mhz

You would have to increase the clock speed by 140mhz or ~16%
Then you'd be at the same clock speed but lacking 176 SPs, so you'd have to overclock an additional 17% (from the perspective of the card running at 1Ghz)

for a total overclock of 1170mhz, only a 36% overclock

 

[Smartazz]

7870 has 1200 SPs @ 1ghz
7850 has 1024 SPs @ 860mhz

You would have to increase the clock speed by 140mhz or ~16%
Then you'd be at the same clock speed but lacking 176 SPs, so you'd have to overclock an additional 17% (from the perspective of the card running at 1Ghz)

for a total overclock of 1170mhz, only a 36% overclock

The 7870 has 1280 SPs iirc.

 

[dennilfloss]

Thanks guys. I decided in the end to buy a 1GHz HIS IceQ X Turbo 7850.

http://forums.anandtech.com/showthread.php?t=2266398

 

[Red Hawk]

Going by Gpureview.com's sliders (not sure how accurate this is), the 7850 needs to be at 1000 MHz in order to match the 7870 at simple pixel fill rate. It needs to be at 1250 MHz in order to match the 7870 at FLOPs and texture fill rate. The 7850 and 7870 have the same memory clock speed and bandwidth.

 

[Madpacket]

I still think the 7850 is still a better buy overall but I don't think the price has really bottomed out yet, they should be at $160.00-170.00 soon. You have to take into account the 7870 also requires an extra PCIe power cable so energy efficiency goes to the 7850 as well.

 

[Concillian]

7870 has 1200 SPs @ 1ghz
7850 has 1024 SPs @ 860mhz

You would have to increase the clock speed by 140mhz or ~16%
Then you'd be at the same clock speed but lacking 176 SPs, so you'd have to overclock an additional 17% (from the perspective of the card running at 1Ghz)

for a total overclock of 1170mhz, only a 36% overclock

It's more than pure SP ratio. The cache, ROP and TMU speed are a significant contributor, and these all scale straight off the base clock.

Exactly how each is weighted depends on the game, but most games see only a 5-7% advantage to the 7870 when both are at the same speed.

 

[OVerLoRDI]

The 7870 has 1280 SPs iirc.

Oops

 

[SickBeast]

Keep in mind that the 7870 is about 25-30% faster than the 7850 in bitmining and compute tasks.

 

[WMD]

That is a 1000MHz 7870?

Edit: At 1920x1200.

This would suggest 1050MHz (according to the preceding page) is close depending on the game.

http://www.anandtech.com/show/5625/...-7850-review-rounding-out-southern-islands/19

In the anandtech article the 7850 had it's memory overlocked as well. Not a fair comparison. But even then it had problems catching the 7870 in some games. My estimates are somewhere between 1050 - 1100mhz.