EDIT: Now thinking HD6870CF (Was: Tempted to upgrade from 6870 to 6950)

[Elcs]

EDIT: So the 6950 seems like a not so good choice. My motherboard only supports x16/x4 CrossfireX.

Would a second 6870 be a decent upgrade or am I leaving myself wide open to issues like microstuttering etc?

From my small amounts of research in the area, it seems like a PCI-E 2.0 slot at x4 won't restrict an HD6870 very much at all.


Original Post:
I have a 6870. My friend is splitting up his 6950 crossfire (one sapphire card, one powercolor card, both are 2Gb).

He's offered me the chance to purchase one of them for £160. The only way I could afford it would be to sell my 6870 for which I would get approximately £100.

Both cards use a 2-fan cooler design so I take it that they are not reference cards. I have no idea about the viability of unlocking either card to a 6970.

He's also not fussed which one he sells onto me so I have the pick of either of them.

If you had the choice, would you spend the £60'ish to go from a 1Gb 6870 to a 2Gb 6950 with unknown 6970 likelihood for resolutions of 1920x1080 at the highest in an i5/8Gb DDR3/SSD rig?

 

[toyota]

for nearly $100, I certainly don't think its worth it as the 6950 is only about 15% faster than a 6870.

 

[jpeyton]

Not worth it. If your motherboard supports CrossFire, get a second 6870; a pair of those will max out most games at 1920x1200.

6870 vs 6950: http://www.anandtech.com/bench/Product/290?vs=293
6870CF vs 6950: http://www.anandtech.com/bench/Product/301?vs=293

 

[Barfo]

No.

 

[Elcs]

Not worth it. If your motherboard supports CrossFire, get a second 6870; a pair of those will max out most games at 1920x1200.

6870 vs 6950: http://www.anandtech.com/bench/Product/290?vs=293
6870CF vs 6950: http://www.anandtech.com/bench/Product/301?vs=293

My board does but only x16/x4? or is it x8/x4? (ASUS P8Z68-V LE). I know it's not the usual x8/x8.

I've read on these boards that it's possible to do it with this board and PCI-E lane configuration without substantial loss of performance of the second 6870 (x4 PCI-E 2.0 lane which is 3.0 compatible, if that makes much difference) but there's a greater risk of microstutter?

Sounds like the 6950 is completely out of the equation.

How does a 2nd 6870 in CF sound if my second PCI-E slot is only an x4?

 

[Jhatfie]

I would be inclined to not do it from a value perspective, there is some performance to be gained for sure, but it would not impact your gaming experience all that much at your resolution. Having owned a 6870 and a 6950 that was unlocked I can honestly say that a better upgrade would be something GTX580/7950 level or higher if you want to notice a real improvement in frame rates.

Now if you are like me and just want to try something new from time to time, it might not be a bad deal and get a boost in gaming power at the same time. Just do not expect a real big difference in performance.

 

[Blastman]

I would wait (if you can) a few weeks and see how the new 7870/7850 pan out. If you can get £100 for your 6870, you might be able to get into a 2GB 7850 for about the same upgrade price as getting that 6950 -- depending on how expensive the new cards will be on that side of the pond in £. With the new GCN architecture + overclocking, the 7850 might be considerably faster than the 6950. There will be a cheaper 1GB 7850 version that you might even consider too.

It's not a bad upgrade, but it's not going to be a big upgrade.

 

[aaksheytalwar]

Expect a 10-15% performance increase in the current gen games at playable fps.

 

[Elcs]

So I went for a second HD6870, installed it and things worked a charm. Noticed it was running at x2 PCI-E in AIDA64 so I went to the bios, told it to act at x4 and it changed. Cheers all round right?

Well, seems like setting x4 decides to turn off my x1 PCI-E ports so if I want it to be in x16/x4 mode, I lose my soundcard. Alternatively I could run it at x16/x2 and have my soundcard (A rather nice X-Fi Titanium Fatal1ty Pro).

Going to run a few benches, run some games and see how it feels. x4 mode CrossfireX definitely feels much better than with a single card. Tested Metro2033 and World of Tanks so far.

Looks like I'll be running either x2 or x4, depending on how things are and be on the search for a very, very, very cheap motherboard that can keep my i5 at 4.7ghz'ish, take my Macho and fit both cards, take my 2TB storage drive, 2x500Gb RAID 0 array and an SSD plus my soundcard all in my 500R case

Thanks for the help guys! Looks like the 2nd card was a good buy and it just needs some unusual and unexpected teething issues to be worked out. No perceivable microstutter so far either!

EDIT: In x16 x2 configuration, my 2nd card does not show in CCC. Looks like I'll be staying at x16 x4 and using onboard audio until such time as I can afford a new motherboard.

 

[omeds]

16+4 ftl. I would have gone for the 6950.

 

[superjim]

You should be able to snag a P67 board with two PCIe 2.0 x16 slots that run in x8/x8 on ebay for $100 or less.

 

[Elcs]

You should be able to snag a P67 board with two PCIe 2.0 x16 slots that run in x8/x8 on ebay for $100 or less.

Import taxes and shipping would kill me

I'll check out P67 Vs. Z68 and see what I can pull up. Maybe even the brand new prices could be nice.

 

[jpeyton]

16+4 ftl. I would have gone for the 6950.

http://www.hardocp.com/article/2010/08/25/gtx_480_sli_pcie_bandwidth_perf_x16x16_vs_x4x4

The difference is negligible at higher resolutions. If you're running a display lower than 1080p, the difference is more pronounced.

http://www.insidehw.com/reviews/graphics-cards/6178-crossfire-x8x8-or-x16x4-the-ongoing-dilemma

We know some users (ehem, website and magazine editors) that changed their entire motherboards just so that they can get one with the x8/x8 mode. This is entirely unjustified and unnecessary, it seems, as the difference in games is minimal. Synthetic benchmarks are more sensitive to the decreased bandwidth of the secondary card, but that’s nowhere near enough to convince us that we’re wrong, and that the x16/x4 configuration is useless. This problem may arise when pairing up two multi-GPU models, but in all ordinary cases, there’s just no base in fact for such a claim. Therefore, if you’re looking into getting a second HD 4850, HD 4870, HD 5770 and similar, worry not, as you won’t feel any difference.

 

[superjim]

x4 is one thing but x2? HardOCP showed that x4 is still pretty good at 1600p or less but I would think x2 would be a much bigger hit.

@OP
I didn't even bother to look where you were from, my bad.

 

[Elcs]

x4 is one thing but x2? HardOCP showed that x4 is still pretty good at 1600p or less but I would think x2 would be a much bigger hit.

@OP
I didn't even bother to look where you were from, my bad.

x2... well I tried setting the slot to x2 but CCC didn't see the 6870 in the x2 lane slot and my PC didn't see my X-Fi so that was a no-go. It might have been a nice stop-gap until I picked up a new board. It's happy at x4 right now but I'm downgraded to onboard sound.

On my location: NP. I'm on a very heavily US oriented site. Advice is usually spot on until it comes to prices and then everything goes belly up.

I was looking at the AsRock Z68 Extreme3 before you mentioned the P67 chipset. Now I've got a few eyes on eBay, looking at a P67 Sabertooth (looks snazzy), ASUS P8P67 Pro (my current board is my first ever ASUS board and I've taken a shine to them) and watching an AsRock P67 Extreme4.

Seems like all of those boards can do what I want though I'd need to do a bit of looking up with the Macho and whether it fits. They all seem to have a few higher end features that aren't on my P8Z68-V LE too so it might end up being a larger upgrade than I first thought.

http://www.hardocp.com/article/2010/08/25/gtx_480_sli_pcie_bandwidth_perf_x16x16_vs_x4x4

The difference is negligible at higher resolutions. If you're running a display lower than 1080p, the difference is more pronounced.

http://www.insidehw.com/reviews/graphics-cards/6178-crossfire-x8x8-or-x16x4-the-ongoing-dilemma

Thanks for the article. I knew that guy was incorrect in his statement but wasn't feeling in the most eloquent mood to disprove his comment.

So far the x16/x4 config and a pair of 6870's is rocking with only some mild issues in games thus far.