When I have my Sony GV-HD700 deck connected via firewire the video playback in my monitor is slow and when I try to lay a sequence back to miniDV via the firwire connection, I eventually get a video overrun error after about 3 minutes because the video can no longer keep up with the output.

Would installing a separate firewire PCIe card resolve this problem?  I'm currently connecting the deck through the 6-pin firewire port in the front (I've also tried the back and get the same result).

And/or would Mojo solve this issue?

Do you have video running all the time to the deck? Is the deck connected to a monitor? Are you doing a Digital Cut or just playing back from the timeline? What are you using for storage? Internal? USB2? Firewire 400 or 800? SATA? Are you rendering all your effects?

The computer display will get sluggish when playing out full quality to your firewire deck.  However it should still work for the most part. The Avid doesn't like any devices on the native firewire ports except av i/o devices, and then only one at a time. You will need an add in firewire card to connect any drives peripherals etc.
Mojo will "solve" this problem. Unfortunately, you will need to switch it out if you ever need to capture hdv/ DvcProHD.

Actually this is one of my pet peeves about Avid. All standard FW i/o that works perfectly in FCP is crippled in Avid. i.e. Try to capture audio using a deck as a transcoder: Can't do it unless you put a tape in the deck and hit record. This is just nonsense. Even straight captures are more problematic in every version after 4.8.4 .
All this B.S. about the new Avid. I'll believe it when their software is just as flexible and capable as FCP.

Answers are below...

Do you have video running all the time to the deck?  I'm only connected to the deck when capturing or laying off.  When I disconnect the deck or deselect "Output to DV Device", video plays normal in both source/record monitors.  It's when I'm capturing or outputting when I run into slow video playback and eventually the video overrun.

Is the deck connected to a monitor?  No, I have no external monitor.

Are you doing a Digital Cut or just playing back from the timeline?  I've done both.  I get the same slow playback in either case.

What are you using for storage? Interal storage - SATA RAID 0 (2TB).  But I can also reproduce the same issue when running off external drive (eg. 1TB eSATA).

Are you rendering all your effects? Yes.

I've ordered a PCIe Firewire card and will try that when it arrives.  Perhaps Avid doesn't like it when the deck is connected through the built in firewire ports (both front & back).

I have Avid Express on my PC laptop and can layback/capture to the same deck via firewire without any of the above problems (usually with an external drive connected via USB 2.0).

Thanks.

Update to the above...

I've installed a separate firewire card (SIIG 2-Port PCIe) and I'm still having the same problem.

How can this be??  I've got a system that's in line with Avid's supported requirements but the deck appears to be drawing enough resources to slow the playback on my timeline (or source material).

Is there a setting I'm overlooking within Avid or perhaps a system configuration setting on my Mac?

Avid wants to connect to the firewire port of the MacPro. What is the codec of your footage? DV? You're going out to a DV deck but you don't have a monitor connected to that deck? You need to. First connect a monitor (or a TV with line-in) to it. Without doing a digital cut, play the video from the sequence, it should play out though the deck if the footage is DV. If some of your footage isn't DV then you'll have problems outputting to a DV deck. Try doing a video mixdown on a top track in DV25 (I always do at least a audio mixdown when I'm outputting).

Are you going out HDV? Then follow the instructions for outputting HDV.

All the footage has been encoded as DV 25 411 MXF.  Why does it matter if I have a monitor connected off my DV deck?  The deck has a built in monitor which I can see just fine.  It won't play the sequence into the deck monitor unless I do a digital cut.  Otherwise, i lose picture.

When I run this through my Avid Express Pro off my PC laptop with a much lower processor/ram, I'm having no problems at all.  Seems odd given my Mac Pro is much more powerful in all aspects. 

Is it worth upgrading to MCS 2.8?

I don't if this helps you, but MC 2.8.4 all set-up accordingly to the "cheatsheet 1.8" is very fine on a G5 (DV + HDV + P2).

DV/HDV Sony deck is attached to the native FW port and media sits on FW800 (PCI card) FW inputs and outputs are OK.

A friend used to run AXP on his G5 too, he had no FW problems either...

I'm talking about "mojo-less sof-only" here, for that matter. So all you gotta do is set it up "by the book" I guees.

It should work. all flakey-avids are misconfigured or running on uinsupported software/hardwre (or a combination of all)

I found the version matrix - not as complete as the cheatsheet, but...

http://www.avid.com/cgi/kbase-redir.aspx?p_faqid=72921&p_created=1154615271&p_sid=SkaL*4oj&p_accessibility=0&p_redirect=&p_lva=&p_sp=cF9zcmNoPTEmcF9zb3J0X2J5PWRmbHQ6MSZwX2dyaWRzb3J0PSZwX3Jvd19jbnQ9MzMsMzMmcF9wcm9kcz0wJnBfY2F0cz0wJnBfcHY9JnBfY3Y9JnBfc2VhcmNoX3R5cGU9YW5zd2Vycy5zZWFyY2hfbmwmcF9wYWdlPTEmcF9zZWFyY2hfdGV4dD12ZXJzaW9uIG1hdHJpeA**&p_li=&p_topview=1