Crossfire 7970 questions and concerns

[GonzoP]

This will be slightly long.

I have a Asus P6X58D-E and one Sapphire 7970 I just got a few days ago.
My mobo has 3 pci-e slots.
The mobo is spec'd to run at 16x/16x/1x or 16x/8x/8x in Tri-Fire. My Dual-X 7970 is so wide though that using it in slot 1 I would not be able to use slot 2. I got my 7970 for a steal of a deal from a local ebayer who cut me a deal since it was local pick up. Just $120 and he has more. So I'm thinking ok. Get another 7970 from him for $120 and just throw it in slot 3. It'll run at 8x and from everything I've read there would be extremely minimal performance loss dropping down from 16x to 8x.
Then I came across this: http://www.overclockers.com/forums/showpost.php?p=6532056&postcount=5
I'd be stuck in the third lane limited to just 1x if I only use slots 1 and 3. While 8x doesn't suffer from performance loss compared to 16x, surely 1x would gimp that second card badly.
This leaves me thinking I'll have to find another smaller 7970 which I would run in slot 1 and then putting my existing wide ass 7970 in slot 2. Right?

I was riding a little old 7870 until this week. Seeing the fire sale on 79xx cards I choose to go that route over a single 290. I mean if I could make the 2nd card work and fit I'd have scored 2 7970's for $240. That is quite a bit cheaper than any 290 I can find not to mentioned superior framerate in ever game I actually play. But now I'm probably looking at trying to find something like the MSI or Gigabyte 7970 which will not impact the second pci-e slot. Sadly, the MSI and Gigabyte cards like most other 7970's on ebay right now are selling in the $175 range. I had originally given myself a $250 budget and was planning on just getting a couple 7950's as those frequently sell in the $125 neighborhood. Then I found this local guy will the killer 7970 deal so I went that route for the first one and I was going to get a second next time I get paid.

Anybody see things differently from how I'm seeing it? I know someone is going to say sell that 7970 for $150 and just get a 290 and that has crossed my mind. In the end though 2 7970's are better performing than a lone 290 especially if the cost is virtually the same or even cheaper to get the 7970's.

Unless I get a 7950. I believe the 7950 will Crossfire with the 7970 yes? There are plenty of MSI or Gigabyte 7950's going for less than $130. In fact there is another ebayer in my town selling 7950's at $130 and I imagine if I played my local pick up card I could get one at $120 or less. I'd have to put the 7950 in slot 1 and the 7970 in slot 2 that way. I was under the impression the superior performing card should be in slot 1 though.

So I guess I'm looking at:
1- Buy a thin 7970 for slot 1 and move my current 7970 to slot 2. This probably takes me out of my original budget plan.
or
2- Buy a thin 7950 for slot 1 and move the 7970 to slot 2. This surely will keep me on budget.

Unless this info in the above link is wrong and I can go slots 1&3 without slot 3 dropping down to 1x with just 2 cards.

My mind is all over the place on this. Kinda looking for some direction. Any help is appreciated. Thanks

 

[Dayaks]

You're going to lose power if you crossfire a 7950 with a 7970.

I personally dislike crossfire. I had 3x 7970s in trifire and like my one 780ti over those three cards, even though my score is ~ 33% lower with the 780ti, everything has smoother game play. To get the smoothness where I wanted it I had to have 70-80 FPS rather than 50. There's a lot of factors there, like how sensitive you are to stuttering, ect. Also some games play like garbage (like Farcry 3) with crossfire. Crossfire generally really limits your overclocks too. It seemed to make more sense to me buy one good card and overclock it OR in reality tri-fire or higher. Crossfire wasn't enough of an increase to counter the microstutters/hitching for me.

That said, the 7970 (280x) is still a pretty powerful card and that's a very low price! I sold my 7970s at ~$400-500 a piece when litecoin went nuts and bought my 780ti. I bought them at ~ 280 a piece.

1x PCIe would be bad for a card that powerful.

 

[primetime]

just one 7970 will play any game out right now no problem...it be a waste of money buying a 7950 to go with it...when the time comes if your not happy get another 7970 or sell it and get a 290.....thats really all there is to it

 

[dook43]

Don't crossfire anything except 290 and above.

 

[GonzoP]

just one 7970 will play any game out right now no problem...it be a waste of money buying a 7950 to go with it...when the time comes if your not happy get another 7970 or sell it and get a 290.....thats really all there is to it

I suppose I could just sit on this one. And yes I have decided against pairing a 7950 with my 7970. With pricing as it is now its hard for me not to get another 7970 for $120-150. Upgrade for the sake of upgrading. Perhaps. But its like my x58 ram. I got all 6 banks filled with 2GB sticks right now. With Deimos confirming 8GB sticks are GTG I'm kinda tempted to take my rig up to 16 or 24GB of ram. Is that overkill? Yeah probably. Just like a second 7970. But I suppose part of it is being [H] as well.

Don't crossfire anything except 290 and above.

And you say that because?


Here's the thing. Just two weeks ago I was sporting a lone 7870. That dreams come true deal on my 7970 for $120 kinda changed my perspective on things. Ridiculous thing is I just sold my 7870 on ebay yesterday for $112.50. Now sure minus ebay and PayPal fees its more like $100 but still yet. It was almost a free to me upgrade. I strongly considered just getting a second 7870. It would have cost me about as much as my 7970 did. But 2 7870's would trump my single 7970 in every game I play right now. Just as 2 7970's would best a 290. I just wonder if 7970 prices will continue to plummet as they have been in recent months. It already seems to be right now is the bottom. Waiting till the end of the year might not change the 7970 pricepoint very much. Now yes its highly likely the 290 will move down in price as the months tick by. But as every upgrader knows you eventually make the plunge and it is what it is when prices fall the month after you buy.
primetime its like the xeons now. When you and some of the other x58ers made the move a month or two ago prices, while good then, were a bit higher. Seeing them where they are now makes you wonder how much lower they can and will go. Just looking at the 5650, the Buy It Now price in March was $129, April was $119, May was $99, June $88 and now they are $74. At this rate they might be asking $50 in September. But again if you justify the purchase at time of sale that's all you can do.

 

[dook43]

And you say that because?

AMD has changed the way crossfire works to allow the best experience on the R9 series. It involves communication over the PCI Express bus rather than a bridge.

Having come from 2x5850, 5970, 2x6950, 7970, 2x7950, I've experienced it on every generation and can stand by this statement.

 

[fanboy]

Don't crossfire anything except 290 and above.

There is the main issuse in thinking what we know.. we need a more updated review to see if AMD worked some magic into the HD7950>7970 and rebrand R9-280 >280X as all those cards should crossfire together. but we have no updated reviews as to how well Crossfire works with frame pacing as the last I saw was before R9-290>290X showed up..

We know that AMD has not forgot them as they support Mantle and DX 11.1 and 11.2 but what about CX .. Kyle ..u game?

 

[hyperion0101]

Don't crossfire anything except 290 and above.

Pretty much this.

Don't Crossfire unless you have:
1. 7970 or below with at least 3 cards
2. 290 or 290X (or any new cards)

With the 290 and 290X, they solved most of the issues with the old microstutter.

Adding a third card to the 7970s, although it did not scale very well at some games and lower resolutions, solved most stutter issues.

 

[GonzoP]

Well you guys have me thinking about this 290 now.
I'm unlikely to find another $120 7970 so I'm probably looking at closer to $160-170 especially for a non reference cooler which only takes up two slots. Which puts me right at the same total $$ spent versus a 290.
The 290's seem to run quite hot though. 90ºC seems to be common and I can't imagine what crossfire temps would be if I added a second 290 down the road.
I could surely sell my 7970 for $150-160 immediately but despite all the crossfire hate I just look at every benchmark review out there and they all have 2 7970's outpacing a 290 by a very sizeable margin at 1920x1200 which is what my 2412 is.

 

[Yakk]

I'm still on 2x R9 280x and will probably be for a good while, works great, no complaints here and I use my CF system daily (see sig).

It just works.

 

[GonzoP]

I'm still on 2x R9 280x and will probably be for a good while, works great, no complaints here and I use my CF system daily (see sig).

It just works.

Yeah thanks for that. OK I guess I'll stick with the second 7970 or a 280x as they're essentially the same. Best deal I suppose I'll go with. If it turns out I'm wrong. Surely I could sell a pair of 7970's for around $300 and just get a 290 to replace.

 

[Venomous]

280x's have the same issue the 7xxx's do in Xfire. AMD has completely ignored mantle optizations with them too. There is no intentions fixing the past and they will continue to play off 280x optimizations in the future as a "later time" excuse.

It's pretty sad

 

[Yakk]

280x's have the same issue the 7xxx's do in Xfire. AMD has completely ignored mantle optizations with them too. There is no intentions fixing the past and they will continue to play off 280x optimizations in the future as a "later time" excuse.

It's pretty sad

I play Thief which was patched to support crossfire Mantle on 280x cards, works very well. DX11 in Thief is a stutter fest on any system, but the Mantle version is silky smooth with minimum FPS doubled that of DX11 to above 60 FPS so there is work being done for 280x cards.

Mantle CPU Usage difference in Thief is also ridiculous, DX11 pegs the i7-920 @ 4ghz CPU at 100%, Mantle CPU usage reaches about 35%.

 

[GonzoP]

I play Thief which was patched to support crossfire Mantle on 280x cards, works very well. DX11 in Thief is a stutter fest on any system, but the Mantle version is silky smooth with minimum FPS doubled that of DX11 to above 60 FPS so there is work being done for 280x cards.

Mantle CPU Usage difference in Thief is also ridiculous, DX11 pegs the i7-920 @ 4ghz CPU at 100%, Mantle CPU usage reaches about 35%.

100 to 35 that's...wow

 

[fanboy]

I have played afew games in crossfire with 280 and 7950 on cat 14.4 which it says frame pacing in on..

BF4 runs dam smooth and I did the work around for War Thunder to get CX working and it may be the best looking game engine I have seen so far and I can't tell I not running a single card as it's that smooth .. the only thing I need to do is find water blocks as the top card is very loud with the fans.

 

[dook43]

Well you guys have me thinking about this 290 now.
I'm unlikely to find another $120 7970 so I'm probably looking at closer to $160-170 especially for a non reference cooler which only takes up two slots. Which puts me right at the same total $$ spent versus a 290.
The 290's seem to run quite hot though. 90ºC seems to be common and I can't imagine what crossfire temps would be if I added a second 290 down the road.

There are zero problems with the cards running at these temps, they are really designed to run at these temps. AMD wasn't lying. There are issues with lockups in a warm climate if you leave the fans at default 47% max in CCC though.

 

[dook43]

I should preface my comments regarding Crossfire by stating my experience has been only while using Eyefinity.

 

[GonzoP]

There are zero problems with the cards running at these temps, they are really designed to run at these temps. AMD wasn't lying. There are issues with lockups in a warm climate if you leave the fans at default 47% max in CCC though.

I should preface my comments regarding Crossfire by stating my experience has been only while using Eyefinity.

Good additions thanks.
I think I will try the second 7970 first. I've only got one monitor. In the debate between getting more 1920x1200 monitors or just going with a single 2560x1440/1600 I don't know what I'd do there. Moderately content with just what I got now.


I do appreciate the continued feedback from everyone

 

[fanboy]

you don't have to spend extra to get CX as the used 7950's sell for around $120 on ebay and will work with your 7970.. with new tech coming we want the cheapest path so the hole we dig is not so deep as many will be off loading $400 to $700 dollar cards soon for the next best thing.

 

[GonzoP]

you don't have to spend extra to get CX as the used 7950's sell for around $120 on ebay and will work with your 7970.. with new tech coming we want the cheapest path so the hole we dig is not so deep as many will be off loading $400 to $700 dollar cards soon for the next best thing.

Oh believe me I know. I was originally going to get a pair of 7950's and had budgeted $125 per card. The 7970 I got fell into my lap at $120 local pick up so I'm allowing myself to get a second 7970 even if I spend $150. In my mind the 2 7970's for $270 is justifiable versus 2 7950's for $250.
I'm all about value. Just got a Xeon 5650 [$70] which I have running at 4.4Ghz on this aging but still kicking x58 mobo of mine. This hexacore cpu especially OC'd has me right there with a 4Ghz Haswell i7. Staved off cpuing my cpu/mobo/ram for another year or two easily.

 

[fanboy]

I have the Xeon x5660 at 3.7Ghz on stock voltage .. BF 4 and War Thunder love this cpu..

 

[hyperion0101]

My advice would be to save up and go for the 290.

More powerful single card > 2 slower cards, even if CF slower exceeds single faster

The reason?

- Fewer issues
- No reliance on driver based optimizations
- Get the latest support (Mantle)
- Can upgrade to a 2nd one later

 

[GonzoP]

I have the Xeon x5660 at 3.7Ghz on stock voltage .. BF 4 and War Thunder love this cpu..

Yeah BF4 certainly does love the extra cores.

My advice would be to save up and go for the 290.

More powerful single card > 2 slower cards, even if CF slower exceeds single faster

The reason?

- Fewer issues
- No reliance on driver based optimizations
- Get the latest support (Mantle)
- Can upgrade to a 2nd one later

Well I've made up my mind but totally respect guys who go a different route.