Fire wire 800 and the 24" imac

I didn't have a problem with an external hard drive with my 24". I have a OWC Mercury hardware raid enclosure that works perfectly on the 800 bus.

Glor

I don't have a drive bench mark tester except xbench, and I don't think the values it reports say much.

Glor

I have a Lacie 1 TB firewire 800 drive that works perfectly with the firewire 800 port on my 24 in. iMac. However, the Lacie fw 800 drive will not work if anything is plugged into the firewire 400 port on the iMac. Fortunately, the Lacie drive also has a 400 fw port on the rear. I have plugged my fw 400 hub into this port on the back of the Lacie and all works well. Apparently the issue is that the firewire 400 and firewire 800 ports on the iMac are both on the same bus and if the fw 400 port is used then the fw 800 bus only works at fw 400 as well. By pluggin my fw 400 hub into the back of the Lacie, I am able to use the Lacie fw 800 drive at full fw 800 speed while all of the fw 400 devices plugged into the hub also work correclty at fw 400 speed.

Tom

Tom,

Have you verified that using both the FW 400 and 800 ports at the same time really gives you full speed on both ports on your imac? (Check the FW speed in "About this Mac" with both connected). The reason I ask is that when I have a FW800(only) drive plugged into my Powerbook G4,, I get FW 800 speed. However, when I plug in a FW device of any kind to the FW 400 port, both ports drop to FW 400 speed. I have a FW 400 cardbus adapter also, and even if I plug all FW 400 devices into the cardbus adapter, I still only get FW 400 speed out of the FW 800 port.

So I am curious if the ports on the new imac are actually independent (like they are on a Mac Pro), or if they continue to share one FW chip. I wish to have a Firewire audio interface connected to the FW 400 port and a fast hard drive connected to the FW 800 port and still get maximum performance out of each. Any further info 2ould be appreciated.

Bob

Oops, edit...

Just reread Tom, that you have the FW 400 devices plugged into the Lacie drive and not the imac FW400 port. I'll have to try that with my setup.

However, the question would still apply to anyone with a new aluminum imac...Are the FW ports independent or do they share a chip like the previous white imac 24" models do? Thanks for any info.

Bob

Bob,

I would suggest that you use the fw 400 port on the back of your Lacie fw drive instead of the fw 800 and fw 400 ports on the iMac. I do not know about the new iMacs (although I'll bet this is still true), but the fw 800 and fw 400 ports on the 24 in. iMac that I have (purchased in March 2007) definitely share the same bus. Fortunately, configured as I explained in my post above with the Lacie fw 800 drive plugged into the fw 800 port on the back of my iMac (with the fw 400 port on the back of my iMac not connected at all) and my fw 400 hub connected to the fw 400 port on the back of the Lacie drive I do get the Lacie drive operating at fw 800 speed and all of the devices on my fw 400 hub work perfectly as well.

Tom

Thanks for the reply, Tom. I also suspect the new imacs share the FW chip across both ports.

I'll try your method of hooking up the FW 400 hub to the FW 400 port on the back of my FW 800 drive to see if that gives me the speed I'm looking for. Thanks for the suggestion.

Bob

Hi Bob and Tom,

It seems they don't share the FW chip, or the chip is smart enough to handle both interfaces at their maximum speed. I have the new iMac and connected a FW800 G-Drive and FW400 LaCie, then as you said, checked in About this computer... Connection and Maximum speeds both match
_________________________________________________

FireWire Bus:
Maximum Speed: Up to 800 Mb/sec
Manufacturer: G-TECH G-DRIVE
Maximum Speed: Up to 800 Mb/sec
Connection Speed: Up to 800 Mb/sec
LaCie Hard Drive Firewire:
Manufacturer: LaCie

Maximum Speed: Up to 400 Mb/sec
Connection Speed: Up to 400 Mb/sec

FireWire Bus:

Maximum Speed: Up to 800 Mb/sec

OXFORD IDE Device 1:

Manufacturer: G-TECH G-DRIVE
Model: 0x0

Maximum Speed: Up to 800 Mb/sec
Connection Speed: Up to 800 Mb/sec
LaCie Hard Drive Firewire:

Manufacturer: LaCie
Model: 0x1

Maximum Speed: Up to 400 Mb/sec
Connection Speed: Up to 400 Mb/sec

I posted the info but the forum seems to be censoring the speeds: 800 Mb/sec for the G-Tech, 400 Mb/sec for the LaCie: both on separate connections.

I don't know if it's related but previous iMacs were using 8 watts shared between the Firewire ports. With the new iMacs, that has changed to 7 watts each.

Eridium,

Thanks for the test. This is very good news. Now I can have my audio interface and FW 400 drives seperated from the FW 800 drives. Probably will make copying between drives a lot faster as well.

Bob

"How did you get yours go fast?
i ordered my iMac on the 8th but it wont get here in till the 15th"

I drove to the Apple store in Century City (Los Angeles) near my house, and they had quite a few (though were running out) soon after the new machines were released. The Apple store employee was kind enough to carry it and plop it in the trunk of my car. I'd like to have a larger internal HD, but I just couldn't wait for a BTO ...

It's a very nice machine, though I had to make adjustments to my room to eliminate glare on the glossy screen. Easily solved.

Since I'm one of the first to get one, it's my pleasure to make tests and share info with others who might be wondering about it ...

Bob,

I am looking to make a purchase pretty soon for audio use and am looking to use my set up the same way you are, (w/ FW400 i/o interface and FW800 hard drive.) Because of this, I'm interested in hearing your experiences.

I was originally looking at the LED MacBook Pro, but because of the same issue with the Firewire ports sharing the same chip/bus and because of the problems I've read with the internal audio (although for my work I'd mainly be using external audio through the i/o interface, I still want it to be working) I am now shying away from the notebook. Since the new alum. iMac just came out, I am now looking into that instead.

What interface and software are you using? I'm looking at the M-Audio ProFire LightBridge. However, I'm proceeding cautiously with this as well, because I've had problems with M-Audio in the past. Furthermore, I've read that the LightBridge, in some cases, can be picky, especially if anything else is plugged into the same firewire bus as it, or if anything is daisy chained to the same port and/or bus. I tried looking for alternatives/equivalents but I mainly need ADAT light pipes and I need to be able to work with Pro Tools.

Therefore, I had the same exact question you asked about whether the 800 and 400 ports share a bus or controller chip.

Please let me know what your using. Perhaps we can share experiences and research.

-Noah

Message was edited by: noahrobd