Reviews - AMD Radeon HD 6870 and HD 6850 cards benchmarked and reviewed

[Terbinator]

Out of curiousity, and without trying to offend anybody - why would anybody buy stock cards?

Surely it pays to wait and see what the non reference cards are like as well as the 69xx range?

The GTX 460 would like a word with you.

[Jimbo75]

Out of curiousity, and without trying to offend anybody - why would anybody buy stock cards?

Surely it pays to wait and see what the non reference cards are like as well as the 69xx range?

My 6850 is going to cost £133 delivered. I know that I can get far superior aftermarket cooling for £30ish. I'd never buy a non-reference card tbh.

[Tarinder]

The Sapphire Radeon HD 6850 cooler is better than the cool-lookin' reference cooler, by the way.

Decent load temps and low-ish noise even when stressed to the limit.

[TheWizard]

The Sapphire Radeon HD 6850 cooler is better than the cool-lookin' reference cooler, by the way.

Decent load temps and low-ish noise even when stressed to the limit.

What manufacturers have released cards with reference coolers? I think HIS but from what I have seen a lot of the board partners have released the 6850 and 6870 with their own cooling solutions. Notably the Sapphire does look a lot different. Do you think that Sapphire have the best cooling out of all the partners?

[TooNice]

Surely it pays to wait and see what the non reference cards are like as well as the 69xx range?

Want to upgrade now? Bang for buck? Especially in the case of the 69xx, by virtue of being higher-end is unlikely to match the bang-for-buck of mid-range card.

[HalloweenJack]

now then - quite a bit of `rumblings` about 6xxx AF quality , if you get the chance could you check it out? from a few accounts its worse than the 5xxx series , even with the 10.10 drivers

[kalniel]

Thought so, seen as its been used on PS3 games. It just seemed odd that its included on AMD slides but not Nvidia ones unless I've missed it being mentioned ofc.

CSAA from nVidia is roughly the same thing, and has been out for ages.

[Terbinator]

From a performance/IQ standpoint - which is better CSAA or MSAA/FSAA?

I.e. is CSAA better looking and more efficient vice versa and so on?

[kalniel]

CSAA is much faster than MSAA/FSAA, it's similar to MLAA in that respect.

Quality-wise it varies, sometimes it's as good, but MSAA is the reference standard, though expensive.

[Rys]

CSAA from nVidia is roughly the same thing, and has been out for ages.

CSAA isn't roughly the same thing at all. One uses subpixel coverage at sample points from the incoming fragments to determine how the pixel is resolved in the framebuffer. The other is a full-screen post-process that can only rely on the already resolved pixels. They both remove aliasing, but that's really where the similarities end. A high level of CSAA will tend to give you better quality than a technique like MLAA, and the latter is really only used because it's cheap and a mostly constant cost in terms of your frame time (so you might as well throw it in there if you have budget), rather than it being really a high quality and robust solution to aliasing.

This explains CSAA reasonably well if you're curious.

[Rys]

CSAA is much faster than MSAA/FSAA, it's similar to MLAA in that respect.

Quality-wise it varies, sometimes it's as good, but MSAA is the reference standard, though expensive.

This is also completely wrong, especially since you can't use the coverage samples on their own without multi-sampling MSAA isn't the reference standard (there's no one way to resolve the multisamples) and CSAA generally improves quality -- although it's not a substitute for just taking more samples -- when used.

Deciding which one is better from a performance/IQ standpoint is only doable if someone measures the performance of the CSAA modes and shows you performance data and videos. Maybe something for HEXUS to peek at when they've got the MLAA driver from ATI, bearing in mind that static screenshot analysis isn't perfect when looking at AA in real-time graphics.

[Rys]

Overall I really like this analysis, having read a bunch of them around the web this morning (it was nice to see the bang4watt analysis in particular and it looks like it holds up despite being a bit wonky with the -100W) and there's no confusion as to where 6850 and 6870 sit in the market just now, and there's a good look at some partner variants too. It frames Barts nicely, so when Tarinder comes to compare Cayman at some point he'll have an easy job.

One thing that stands out is saying that MLAA is implemented as a DirectCompute shader. Does that mean it's limited to just DirectX-based games? It's hopefully API agnostic in the end and not just a patched shader only working with DirectX.

[kalniel]

Which one am I thinking of then? I can't remember the name of it.

Good to see you back around Hexus, Rys. Is Beyond3d still going?

[Terbinator]

I know the 'Q' ones have a negative effect on IQ as its just like rubbing Vaseline over everything.

[Rys]

Are you thinking of Quincunx? That was a blur in the DAC so it never looked great, but performance was always good

B3D is still going, kalniel, although at our usual glacial pace (we just published on Fermi on Saturday for example, 7 months after everyone else)!

[Terbinator]

Are you thinking of Quincunx? That was a blur in the DAC so it never looked great, but performance was always good

Yes. When DigitalFoundry have gone over its implementation in PS3 titles it looks awful compared to the usual 360 MSAA counter-parts.