Technology in terms you understand. Sign up for the Confident Computing newsletter for weekly solutions to make your life easier. Click here and get The Ask Leo! Guide to Staying Safe on the Internet — FREE Edition as my thank you for subscribing!

Why didn't my gigabit network card result in better performance?


I recently installed a Gigabit PCI card on my Dell Windows XP SP2 system.
I’m running on a Cable LAN system and was hoping to see at least a small
improvement on the 100mbps of the old card. I’m not complaining because
everything is as was before the install,just wondering if there is a little
tweak I should have carried out to help it along?

It depends on what it was you were expecting to change.

I ran into a very similar situation when I upgraded one of my switches to
gigabit and saw only a marginal performance impact. So I started looking into

First, let’s make sure you’ve actually covered all the bases.

Become a Patron of Ask Leo! and go ad-free!

In order for a gigabit (or 1,000 megabit) connection to happen, the
equipment at both ends of the wire need to be gigabit-capable. You indicated
that you purchased a gigabit ethernet card, but what’s it plugged into? If it’s
a router or other device that’s only capable of 100 megabits, then the
connection will happen at the slower speed. You can’t force a gigabit into a
100 megabit connection.

Similarly, if you’re copying files between two machines, then both machines
must have gigabit-capable network connections for you to be able to take
advantage of the higher speed.

And if you’re expecting your gigabit network card to somehow improve your
internet speed, then you’re going to be very disappointed. Your
internet connection already has a maximum speed – a cable connection might
occasionally go as fast as 10, or even 50 megabits, but that’s slower than the
card you already had! Putting in a faster network card will not speed up the
internet connection provided by your ISP.

“Putting in a faster network card will not speed up the
internet connection provided by your ISP.”

So far I hope all that makes sense.

Now, let me tell you about a scenario that isn’t nearly as clear, and had me
puzzling over it myself for a while.

My desktop machine came with a gigabit ethernet adapter. I decided to speed
up the connection between this machine and a backup machine by installing a
gigabit ethernet card in that machine and connecting the two through a gigabit

Now, even though a gigabit per second is 10 times faster than 100 megabits
per second, I didn’t really expect a 10x increase in speed, there are too many
other factors at play. What I didn’t expect was that the increase would be more
like 2x. My ten-times-faster gigabit connection was copying files
machine-to-machine only twice as fast as my 100 megabit connection had.

Clearly the gigabit connection had some effect, since there was a
speed up, but it wasn’t what I was expecting.

My assumption was that there was another choke point in the system. Just
like the gigabit connection to your ISPs internet connection will never be any
faster than whatever the ISP gives you, there must be something else in my
system that was slower than my newly speed gigabit connection.

And indeed there was. I did some tests and discovered that the gigabit
connection was faster than the transfer rate of my hard drives. The hard drives
had become the slowest component in that machine-to-machine transfer. While the
network was capable of faster speeds it was being held back by the work
required to actually get the data on and off my hard drives.

Does this mean that the gigabit network is pointless? Hardly.

While in the past that machine-to-machine copy might have actually saturated
my network, since the 100 megabit network was at that point slower than the
hard drives and hence the limiting factor for the copy, now the copy could
proceed at the hard drive’s full speed, and still leave lots of network
bandwidth for other traffic. Other machines and other network activities could
continue without being nearly as impacted by something that would previously
have used up all available bandwidth.

In practice, do you care? Probably not. At least not yet. As always, speeds
and needs will increase so that eventually that 100megabit network will seem
slower than molasses compared to future technologies.

But for now, for most home and even small business needs, a 100 megabit per
second network is plenty.

And upgrading may not even get you the increase you were expecting.

Do this

Subscribe to Confident Computing! Less frustration and more confidence, solutions, answers, and tips in your inbox every week.

I'll see you there!

8 comments on “Why didn't my gigabit network card result in better performance?”

  1. Thank you for this article. I did the same thing you did, hoping to get much faster performance out of my small 4 node home network. I have 3 machines fitted with Gb network cards and put them all a Gb switch. My transfer rate between 2 machines has been 7 Mb per second or somewhere near that. One machine has a Western Digital Raptor X HD serial ATA supposedly capable of 3 Gb per second transfers. The other machine has a maxtor IDE 300 Gb machine, not sure the the max transfer rate is supposed to be, but I will check later. The WD machine has a quad core processor and ddr3 ram, and the other is a P4 prescott 3.0 MHz machine.

    Are they any other possible bottlenecks you can think of? I did a tracert and it said 1 hop to the the other machine, does that mean it’s not going through the router that I have connected at all? I am using Cat 6 cabling. Any thoughts?

  2. Also make sure you’re using Cat. 5E network cables. While Cat. 5 cables may function to some degree in a gigabit Ethernet, they perform below standard during high-data transfer scenarios.

  3. The two computers on my LAN have gigabit adapters.They are both connected to a Netgear WNR854T gigabit router. The router configuration manager offers no setting option for Full-Duplex mode. Does my router need 1Gbps full duplex capability in order to transfer files at true gigabit speed across my LAN?

    Hash: SHA1



    Version: GnuPG v1.4.7 (MingW32)


  5. Any thoughts on why my Marvell Yukon 88E8056 network adapter on an ASUS motherboard won’t connect with gigabit speed to my gigabit switch? The motherboard has two network adapters, both connect at 100 Mbps. My NAS connects to the same switch with 1 Gbps. Can’t find any settings for this in the control panel – I’ll try other cables and other ports when I get back home

  6. Hello. I was wondering if Robert Williams of the first post ever got a resolution to this? I am having very similar issues that he is. Thanks, Jason

  7. The max transfer rate of the PCI bus is 133 MB/s, which is shared across other components.

    The max transfer rate of PCI Express is 250 MB/s and is a point-to-point connection which means no sharing.

  8. Hello,
    I am going to upgrade my network of 50 PCs which working on 100mbps switch or having Cat5 cable .Now i am going to buy gigabit switch or Cat6 cable to update my wire or my device but my all system having in-build 100mbps of LAN card .so that up-gradation of my device or cable give me better performance then earlier ???
    or Should i have to do up-gradation in my system LAN card like installed a Gigabit PCI card on each system for get better performance in my Local network ? or its work fine without upgrading the Gigabit PCI card on my system.
    reply soon…..


Leave a reply:

Before commenting please:

  • Read the article.
  • Comment on the article.
  • No personal information.
  • No spam.

Comments violating those rules will be removed. Comments that don't add value will be removed, including off-topic or content-free comments, or comments that look even a little bit like spam. All comments containing links and certain keywords will be moderated before publication.

I want comments to be valuable for everyone, including those who come later and take the time to read.