Well, to answer my own question -

We all know that a PCIe 2.0 graphics card will run fine on an older PCIe 1.0 motherboard.  I've done it.  It works.  If your mobo supports PCIe bus overclocking it will help it run faster still - the faster Graphics card will gobble up this extra data bandwidth.  And the volume of data generated and transferred from my dual cored Opteron 185 CPU on my PCIe 1.0 mobo is not bottlenecked by the slower PCIe 1.0 bandwidth (which this type of set-up defaults to) on the way to the PCIe 2.0 Graphics Card.  The graphics card still runs at full tilt, so any Frame Rate issues here would be with the Opteron processor being 'only' a dual core and not processing the game code with the same gusto as a modern 4 or 8 core CPU. So all's well and good with the graphics card.
Now I have two of these PCIe 2.0 graphics cards and my PCIe 1.0 mobo is a Crossfire.  So, what do I do?  You bet I Crossfire them!
Ah -

It doesn't work to improve performance.  In fact it takes 5 to 10 frames per second off the performance. 

My guess is that for Crossfire to work, these PCIe 2.0 cards need to talk to each other faster than my PCIe 1.0 mobo will let them.  They try.  The Crossfire set-up runs - but terribly slowly - slower than just one card alone.  Should not the Crossfire be alerted?  Be told to scale its activities in the interest of performance enhancement?  Am I in the right area with this line of questioning?
Any thoughts?
Still, on the bright side I now have three OpenCL devices in my system (including the Opteron) so SETI@home will get a lot of help.  But I'll just deactivate Crossfire when I want to play a game.  That, I can tell you, does work!
Thank you.

Oh, my set up is:
Asus A8R32-MVP DeLuxe motherboard (ATI Crossfire Xpress 3200 chipset).
Opteron 185 CPU.
4GB RAM (DDR).
160GB RAID 0.
2 x Sapphire HD6950 OC Edition graphics cards.
Windows 7.
DX11.

So you spent all this time telling us stuff we already knew? Oh, and that statement



Is...wrong, and is extremely dangerous. People run it at 105-110 for benchmarking purposes, but anything higher than 100 can result in things such as SATA drive data corruption.

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Crosshair IV Formula, Phenom II x4 965 w/ Corsair H60, 8 GiB OCZ Platinum DDR3 1600, XFX HD 7970 Ghz, 512GB Vertex 4, 256GB Vector, 240GB Agility 3, Creative X-Fi Titanium w/ Creative Gigaworks S750, SeaSonic X750, HP ZR2440w, Win 7 Ultimate x64

Oh knowledgeable Wizard, grant me an audience.

I fear my recklessness in this matter has not paid off in performance - only experience.  The reason I am on this long and risky upgrade path is because of a strategy I committed to a long time ago.  A time when PCIe 1.0 seemed so amazing that I could not possibly foresee an upgrade arriving for many years to come.  How wrong I was.  How quickly things changed.  How wrong I was to think that software vendors would not adapt to multi threaded CPUs as quickly as they did.  And how easily the new PCIe bus grew into the ethereal entity it is now.  How much cheaper RAM would become - and it is much cheaper for DDR2,3+ than my old DDR1.  Amazing things have happened - none of which I thought possible when I drew up my long-term money saving plans to upgrade one part at a time all those years ago.  I have arrived (time to upgrade - have a look at what's available) in a world so changed that I barely recognise the things I see around me.  Experience.

So please forgive my recklessness - it was driven by optimism!  By hope that the industry would sit on its laurels and rest a while, bathing in the light of what had been achieved with PCIe 1.0 and dual core CPUs.  I was to take advantage of this lull in proceedings - Ha!  Recent progress has been as swift as I can ever remember.  I didn't think this would happen.  I was wrong.

Thanks for your answer.

PS
I notice you have a modern CPU, a Phenom. Tell me please: With the clock rate of 3.8GHz does the old formula of times 1.6 still apply? Does this mean your Phenom has an Intel equivalent speed of 6GHx? I mean - Does it??

Thanks.

Well....  It flies!  SETI@home doesn't know what's hit it.  And I don't need Crossfire enabled - the project manager sees all OpenCL devices and assigns work units whether Crossfire is on or off.  Cool.  And by golly it really does work quickly!

Thanks all.

If aliens overrun Earth you'll be the one to blame...

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CPU: AMD Phenom II X4 810 @ 3250MHz | RAM: Kingmax 2x2GB DDR2 800 @ 833MHz| MoBo: MSI K9A2 CF v1.0 (BIOS: 1.D)| GPU: Asus HD 6850 1024MB (DirectCu) @ 850/1100MHz | Display: Chili Green Vision L24FHD | PSU: PC Power & Cooling Silencer 750 Quad | OS: MS Windows 95 x64 Edition

CPU: Pentium 4 Northwood S478 @ 3200MHz | RAM: 1,5GB DDR 400| MoBo: Gigabyte GA-8S661FXMP-RZ | GPU: Abit Geforce Ti 4200 | Display: Dimarson 19" CRT | PSU: Noname 400W | OS: MS Windows XP Pro, Fedora 18

If they're still using radio it's more likely they'll crash into us!

- A faster than light technology capable race that did not master ftl communication by entanglement (or some such future marvel) will end up chasing thier own carrier waves!  I'm doing my bit .

PCI Express 2 is backwards compatible, so any PCIe 2 devices on a PCIe 1 bus will just downclock to 1.0 speeds.

As far as crossfire goes, if you're not seeing any performance boost at all, then your software must not support it.  There's a lot weird things that can happen in a multiGPU system, and it's far from being a magic bullet, but there's almost always some benefit from adding a second card... assuming your software can actually make use of them simultaneously.

If SETI is your only concern, I'd say not to bother with crossfire at all.  What I said above applies only to frame rates, and there's more to the whole gaming experience than how many frames are displayed in a given period of time.  Frame latency is often a different story where adding a second GPU isn't always the best idea.

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Do not meddle in the affairs of archers, for they are subtle and quick to anger.
Post Count: +8510
Troll Hunter

The opinions expressed above do not represent those of Advanced Micro Devices or any of their affiliates.

Edited: 01/12/2013 at 07:51 PM by Mime

It was a gamble of mine - I'm not a professional you may realise!  It's a shame , that's all.  None the less, I am pleased with the crunching I'm doing for BOINC.  I'm very impressed actually.  I heard about OpenCL technology about the time I took the shot - the gamble - it must have been in the back of my mind that either way, good things will come out of it, and they have.  OpenCL is brilliant!

On a lighter note, I will still be looking at 2nd hand mobos/CPUs/RAM.  I mean all I need is a PCIe 2.0 set-up and surely there'll be plenty of that now that PCIe 3.0 is on the market.  Fingers and toes crossed!

Thanks for your encouraging words -

Please, if I may offer some words of explanation - BOINC (Berkley Open Infrastructure for Networked Computers) has more to offer than just SETI if that's not your cup of tea.  I personally am interested in physics so I'm also crunching numbers for Einstein@home (the proving of Einsteins theory about gravity) and LHC@home (the Large Hadron Collider in Switzerland - although the LHC@home project is not yet set up to use the GPU but there are plenty of others that do).  BOINC offers the chance for you to help any number of these projects crunch numbers and solve problems. It's not just Physics. Chemiistry, Biology, Medicine, Astronomy, Pure Math, Artificial Intelligence, Earth Sciences - you name it.

See http://boinc.berkeley.edu/projects.php for a comprehensive list.

My second HD6950OC helps my efforts immensely. Together they crunch the reams of raw data from those real experimental physics instruments, each one faster than the CPU which is quite amazing to witness.  And I'm amazed at how well a singular HD6950 maxes out the quality settings of Far Cry 3.  So I'm cool with it.  And eager to carry on crunching.

Regards.

Highest I would set pcie bus freq is 105, the absolute max that I would ever go, best leave it at default 100, it should only be used if you need to stabilize an overclock and can't get past crashes even if volts are raised.

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I'm thinkin the people at Stanford who run the project probably aren't thrilled about the prospects of overclocking either.  One machine that finishes its work units a few hours early can't really be helping that much compared to that machine at stock, and throwing out or delaying batches due to rounding errors, and the other types of things that sneak in due to overclocked systems has gotta be annoying.

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Do not meddle in the affairs of archers, for they are subtle and quick to anger.
Post Count: +8510
Troll Hunter

The opinions expressed above do not represent those of Advanced Micro Devices or any of their affiliates.

My mobo has a wealth of OC features but I leave that stuff alone - I'm not very patient/good at it!  The feature - and I should have made this clearer - is a dedicated setting for the 'PEG Link Speed'.  Its options are:

Slow , Normal, Fast, Fastest.

and that's it!  It does make a slight difference too - about 5 FPS.  Other than that, all timing settings are default factory.  For such an old set-up, it totaly rocks! (To a certain extent..)