(solved) Doubts about Flex cards

[Moose]

EDIT: look at this new thread I recently started, because the Flex cards are no longer available. In the new thread a similar option gets discussed.

Hello people,

I've recently ordered an AMD 6950 Flex because I thought it was the only way to evade all the problems regarding flickering if I want to use 3 DVI/HDMI monitors.
However, on youtube and on this forum there are a lot of people that run three monitors in Eyefinity on cards such as the 6970. And they have no problem at all running games.
So I was wondering:
-Do these people all have active displayportadapters or have displayport monitors?
-Or do these people just connect 2 monitors to the 2 DVI and connect the other monitor to the HDMI port?

I doubt point one because displayport monitors cost tons of money, and so do three active displayport adapters.
I doubt point two because connecting your three monitors that way is the reason flickering happens and to prevent that they released a Flex edition.

Can anyone please help me with this/give me some information?

Moose

[Skid]

The screen flickering issue was largely resolved a while ago, I think it was a hardware issue, none of the 69xx line should have it. Personally I use two active DP to DVI adaptors, one DVI, then the HDMI to my TV on my 6950 (flashed to 6970 bios). I've never had an issue with flickering, just one monitor turning itself off when the adaptor went doggy, I do get screen tearing on my DVI monitor if the frame rate starts to fluctuates allot.

I thought the flex version was actually release to allow you to connect more monitors at once, but someone can correct me if I'm wrong on that.

[Moose]

That was it! The screen tearing issue. Could you tell me exactly what causes screen tearing and what can be done about it? Because I'm sure I've read somewhere that the Flex edition counters the screentearing problem.
It also has something to do with v-sync, doesn't it?

Moose

[Delphium]

The vast majority of users use an active DP to DVI adaptor without tomany issues these days, now that there is better compatability with adaptors.

Personally I use 2x passive DP>DVI adaptors and 1x active DP>DVI-dual-link adaptor as I am using a 5870E6 card which has only DP outputs.

Since day 1 when I got my kit I have never experienced tearing, I did have some screen flicker, but I found out that was due to the core and mem clocks changing back and forth when using Overdrive in CCC to overclock the card.

My resolution to the flickering when using OverDrive can be found here... http://widescreengamingforum.com/forum/forums/multi-monitor-gaming/amd-eyefinity-discussions/15402/ati-overdrive-low-2d-clocks-causes

This may also work when not using Overdrive, but as I did not have a problem with it off, I have nothing to test with.

[skipclarke]

I wouldn't say that monitors with DP ports cost "tons of money". The Dell U2212HM is a 21.5" IPS panel with DP and it's $219. Granted the lower lines of monitors don't have DP, but for $219 you're also getting an IPS panel. The HP ZR2040w is $189. It's a 20" LED backed IPS monitor, and it has DP.

SINGLE link active adapters are only $30. You're probably thinking of the old Dual-Link active adapters that cost more than $100 and required USB power and were problematic. I'm going to be posting a review of a Flex HD 6770. I can tell you that I used the included DP>DVI and HDMI>DVI adapters, and it simply worked. I had some flickering on the bottom of the monitors if I had three plugged in and configured as extended desktops. Two didn't flicker, and enabling the Eyefinity config didn't flicker either.

[Moose]

Thanks a lot Delphium and Ibrin.

First of all, I already have three monitors. It are three IPS panels, with D-Sub (VGA), DVI-D, HDMI as video-input. I hope this means I can use single link active adapter.
IF the answer is yes, does that means I can use, for example an 7970, and connect the monitors as following: two monitors to the two DVI ports on the card, and the remaining monitor connected via a DP to HDMI/DVI single link active adapter?

IF, however, the answer is no, does that mean I have to buy expensive adapters or a Flex edition?

One final question: I absolutely want no flickering OR screentearing at all. Does the problem you encountered occurs to more people?

[Delphium]

IF the answer is yes, does that means I can use, for example an 7970, and connect the monitors as following: two monitors to the two DVI ports on the card, and the remaining monitor connected via a DP to HDMI/DVI single link active adapter?

This is correct, single link adaptors are around the $30/£20 mark as ibrin stated.

[Moose]

So DVI-D is compatible with active single-link? Great to hear that!

I just need to know the answer to my last question :p

[skipclarke]

As long as you have 1920x1200 panels or smaller, you are good. On any 6000-series or 7000-series card, the reference design on the DVI ports is the primary is DL-DVI (up to 2560x1600) and the secondary is SL-DVI (up to 1920x1200). You can plug DVI into both of those for 1920x1200, then use a SL-DVI active adapter on a mini-DP port for a 3rd 1920x1200.

If you want 3x2560x1600 or 3x2560x1440 that takes 2x DP + DL-DVI, or two DL adapters on the DP ports.

I've never had issues with tearing, so I can't say any technology offers a "solution". However, I ran the 6770 Flex through days of benchmarking and never saw any tearing. Nor have I had any on my 7970.

[Moose]

I've got three 1920x1080 panels, so that'd be okay. Now it's up to me to choose:

-Buy an AMD 6950 Flex and just connect two monitors in the two DVI ports on the card and the remaining monitor on the HDMI port on the card.
This means: no hassle with adapters and not having to worry about two different digital signals (DVI andHDMI).

-Buy and AMD 6970 or 7970 and connect two monitors in the two DVI ports on the card and the remaining monitor via an SL-DVI active adapter on one of the DP ports on the card.
This means: extra costs for the adapter and videocard and worrying about tearing because I've got two different digital signals (DVI and DP).
However, going for an 6970 of 7970 gives me the option to play games on higher settings.

Can anyone help me decide what I should do (maybe based on experience) and give some arguments? Also, if you recommend option 2, then please add how I should overcome any problems regarding tearing due to FPS fluctuation:

I do get screen tearing on my DVI monitor if the frame rate starts to fluctuates a lot.

PS: Sorry I'm asking so many questions, but this is really important for me. It's a lot of money and I don't want to ruin it.

[rdqlus]

Buy a 7970. If the screen tearing bothers you then buy an DP 1.2 MST hub (once they're available) and 3 DP->SL-DVI adapters. Buying a 6950 at this point to drive a 5760x1080 setup is bordering on foolish. I'm running a 5870E6 right now and can't wait to upgrade (it's about 5% shy of the 6950 you're considering).

M.

[suiken_2mieu]

You know I don't see why the flex cards would produce tearing because electrically DVI and HDMI are equivalent.

[Moose]

Buy a 7970. If the screen tearing bothers you then buy an DP 1.2 MST hub (once they're available) and 3 DP->SL-DVI adapters. Buying a 6950 at this point to drive a 5760x1080 setup is bordering on foolish. I'm running a 5870E6 right now and can't wait to upgrade (it's about 5% shy of the 6950 you're considering).

M.

Thanks M, that's helpful. You know, I could just get a 7970, buy 2 DP->SL-DVI adapters and hook up the other monitor to the DVI port. Then, when the DP 1.2 MST hub comes out, I can buy that and get another DP->SL-DVI adapter. That way, I do not have to wait before buying a 7970. However, do DP->SL-DVI adapters cause input lag? I've already got 14ms on my monitors :/

[Moose]

You know I don't see why the flex cards would produce tearing because electrically DVI and HDMI are equivalent.

If you read carefully you will see I said: "Getting a Flex card means I do NOT have to worry about tearing.

[rdqlus]

No, I don't think they'll introduce any notable lag. The adapters should only have enough memory to hold at most a few DP Transport Units (way less than a raster line). To put more memory in the adapter would just cost more with no benefit at all.

[Moose]

So I guess it's obvious I should buy and 7-series and then a Displayport hub.
1. Should I wait for a 7-series Flex edition is released (not the 6gb one) or should I just buy the 7970?
2. How long before a DP 1.2 MST hub is released?

Thanks, Moose

[ryde]

I'm in a similar position as Moose and I was thinking of going with the 6G and three dp2dvi adapters ... Pricy option but should be on the safe side regarding tearing.

[Moose]

Does anyone know whether they'll be releasing an AMD 79xx or 78xx 3GB with three mini DP ports? Cause I'd reckon for three screens 3gb should be enough.

Also, if I buy an AMD 7970 I'd probably have tearing on one of the monitors because two are connected via mini DP and one is connected via HDMI/DVI. Is there anything that can be done about this? I believe tearing is caused by rapid fluctuation of ingame FPS. Turning V-Sync on would seem like a solution, but in order for that to work you'd have to reach the 60 fps first. Am I getting the right conclusions here, and is there any other workaround to prevent tearing?

If buying a hub which connects three DVI/HDMI ports to one mini DP port is the only solution, could you add an estimated price and release date with that?

[Haldi]

Not sure if you get Tearing on a HD7970 !
1. It's a new GPU generation.... i thought HD6970 vs 5870 was a major improvement with Tearing issues.
2. There is a mini-DP to DVI Adtapter included! IF AMD manages to produce a Adapter which will produce flickering! nah.... quality control just CANT let something like that happen! Would be realy disapointed by AMD!


but.... are there realy Mini Displayport hubs out there? always hear romours bout them. but never saw one!

[rdqlus]

Ok, so I don't think the tearing is due to rapid fluctuation of in-game FPS. My day job is design and verification of DP/DVI silicon so I may know what I'm talking about. My best guess is that the DP and HDMI/DVI pixel clocks aren't in sync. DP 1.1 runs at 1.62Gbps or 2.7Gbps and the pixel stream is packed into transfer units with filler bytes. While DVI/HDMI is a different rate depending on the resolution. If 2 links are DP and one link is DVI then they aren't necessarily running in lockstep. The aggregate effect is that while the DP monitors may be running at 60Hz the DVI could be at 59.97Hz (for example) and it will appear as tearing on the DVI monitor since the frame buffer won't switch to the next frame for all monitors during the vertical blanking period.

The solutions are to:

i) use 3 matched ports that are synchronous to a single clock
ii) use a DP 1.2 MST hub
iii) have AMD clock the DP pixel clock with the DVI link clock inside their chip (which is likely impossible due to some hardware constraint)

The last chip I worked on supported DP and/or DVI links. From a purely data output perspective we'd have the same screen tearing problems (ie: we don't clock our video output links from a single clock) but we get around it with a *complicated* image engine/buffer.

Note: I don't work for nVidia or AMD.