Cannot Get Anywhere Near Gigabit Network Speed between Macs and PC

I've disconnected the router and internet connection, etc. to keep it simple.

There is one 10/100/1000Base-T Gigabit switch.  D-Link 1008-D.  All cables are normal (not crossover) CAT-6 and they are all less than 20ft. long.  There are three computers connected to it.  Two Macs and one PC:

2 Macs - Both are G5 dual processor 2.5ghz with built in gigabit ethernet.  Both running OSX Panther 10.3.5.

1 PC - P4 2.6ghz MSI PT880 motherboard with a built in Via Gigabit ethernet adapter.  Windows XP Professional SP-1.  Clean installation was just made with BIOS and drivers all updated.

The computers all see each other just fine.  This was never an issue.  Furthermore, transferring between the two Macs is fine- I get gigabit speed.  The problem is that transfering between the PC and either of the Macs, I get very, very, very slow transfer speed.  About 10Mbps or 1 MB per second.

This has been the case whether or not the Macs have Appletalk active or not, and whether or not Windows sharing is active or not (with Windows sharing inactive, the Macs can still see the PC).

The PC's motherboard came with a utility called "Via Gigacheck" which seems very complicated and advanced.  Runing the diagnostics, it says everything is A-O-K and that there is a good quality Gigiabit connection between the PC and the network switch.

The switch shows green lights for 1000 connection, and amber lights for 100 connection.  All the lights for all three ports are green.  So there is a gigabit link connecting them all.

Please do not respond with nonsense about the hard disks or the PCI bus on the PC creating a bottleneck.  I've been testing RAID0 to RAID0, but even the slowest hard drive on the planet at this point is still faster than 10Mbps.  Furthermore, the PC has the Gigabit adapter built into the South Bridge, which means that it does not go through the PCI bus.

I have wasted an entire work day trying to figure this out.  I am desperate.  Thank you.  I've been saving these points for something very important and this is it.
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ee_ai_constructConnect With a Mentor Commented:
Question answered by asker or dialog valuable.
Closed, 500 points refunded.
ee_ai_construct (replacement part #xm34)
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Do you know whether the PC is using full or half duplex?
Is the speed a problem in both directions?   Meaning, copying to the PC from sitting at the Mac and copy to the Mac from sitting at the PC?

Assuming yes, can you force 100 Full on the PC and see if you get 100 Full performance out of it?

We did have a computer that had a GigE built in it that the performance was horrible and when we installed a card and the problem went away.

It turned out the onboard GigE had a relatively small buffer and it had to build each GigE packet on the fly.  It wasn't really fast enough to keep up with the demand of GigE so it would stop sending until the packet was built.

The 100 Full test could verify that is a problem.

Something to note:
Most common traffic creates small packets of information.  Since GigE uses large packets, there is often a lot of wasted space in each packet.  You might find that 100 BaseT will be faster for most common stuff.  Large files will definitely benefit from 1000 though.
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This article has a relevant comment :

"...The VT6120 chip present on our reference board features Cicada Semiconductor's SimpliPHY technology, which Cicada uses in its own 8200 series of Gigabit transceivers.  The 196-pin LBGA chip communicates over the PCI bus, which would suggest a performance disadvantage.  ... "


"..maximize the use of packet bursts for efficient PCI bandwidth usage"

would suggest that your comment about the gigabit nic not being on the PCI is incorrect.

I would assume the limitations of the PCI bus are part of the problem.

But even at 1066.7 Mbit, the PCI bus should be able to do better than 100 BaseT, which he said it was doing far worse that even that.

I noticed a huge improvement when I turned off the onboard GigE and installed a PCI GigE card.
OK, fair enough. I was really countering the assumption that the gigE traffic does not use the PCI bus. On the G5s, the gigE NICs would be on the PCIX bus, I assume.

However, "About 10Mbps or 1 MB per second." does seems a little slow, under any circumstances.

However, I am not sure about where the hard drives are connected. If they are on the PCI bus too, then there would be (massive) contention. On the other hand, if they are on the VIA Drivestation which, from, does not seem to use the PCI bus, everything would be OK.

Finding detailed information on the architecture of the Apple seems to be more difficult :( Most of the stuff I can find is more marketing oriented - even the white paper doesn't go into much detail.

Anyway...10Mbps is still too low, I think, for PCI to be a problem, but it's worth bearing in mind.
lifterusAuthor Commented:
I solved the problem myself.  The correct answer to this problem (which I would have awarded points to) would have been "There are no strange compatibility problems or additional software required to do gigabit networking between OSX and XP".  It should work 'out of the box'.  Instead I get "your bus/drives are not fast enough" answers which I specifically asked not to be posted.

1) This NIC does not use the PCI bus.  At least it is advertised as such.  Just because another board with the same controller does, doesn't mean this one does.

2)  It makes no difference anyways.  A 32-bit PCI bus does not restrict bamdwidth to 1 MB per second.  I'ts 133 times faster than that.

Thanks for trying to solve the problem.  It turns out the motherboard I bought is not to spec and is defective or was damaged.  It was an open box item at Frys Electronics, so the previous customer could have damaged it.  Whatever it is, the network controller does not work and I can definately verify that it is a hardware malfunction.  I've tried several BIOS versions of the board.  Some of the versions literally will not even turn on the network controller even though it is enebled in the BIOS menu (no link light or anything).  The BIOS revisions that do power the NIC, give me this problem of very, very low speed.

The problem was that all along I thought there was some sort of Mac to PC issue going on.  I saw software for sale like "Appleshare IP" and "Windows Advanced Server 2003" available and thought maybe I needed that.  That was not the case.  I bought a new (different) Supermicro motherboard and I now get Gbps transfers between the Macs and the PC- right out of the box.  Thanks again for responding.

Less of the attitude, please. I don't care about 'points' whatever those are.

I am aware that you think that the NIC doesn't use the PCI bus, but the references I gave are for the board you specified, and specifically say otherwise - even on the manufacturer's web site.

You also did not specify if the hard drives were also on the PCI bus, which would have a negative impact on performance.

Even considering this 'worst case', I commented you are still probably not seeing enough bandwidth.

I sorry you didn't think my response were helpful. I didn't think your response was polite - please try harder.
lifterusAuthor Commented:
Sorry if I sounded rude to you, but I did specifically ask that nobody travel down that route, and yet it happened.  As for whether or not the the adapter uses the PCI bus is totally irrelavent.  Even if it did, and the disks were on that bus (which they are not) I would not be getting <10Mbps speed when the 1000Mbps link light is on.  Thanks for trying to help though.  As for the points comment, it was directed to the moderators so they can close the topic; it was not directed at you.
My first response didn't point to any bottlenecks (and in fact wrote a message to the contrary) and did seem to indicate that it was a hardware problem.  Since the original message said

"The PC's motherboard came with a utility called "Via Gigacheck" which seems very complicated and advanced.  Runing the diagnostics, it says everything is A-O-K and that there is a good quality Gigiabit connection between the PC and the network switch."

I decided to rule that possibility out, but did leave it open to problems with the GigE interface with regards to my own experience.

I'm glad you figured it out.  I just wanted to point out that you had also said the onboard was working fine according to the test.
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