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I have few question and I don't find right answers.

  • What's the maximum speed of an Ethernet cable (not a phone cable! the one that has 8 threads)
  • About the Gigabit Ethernet Network Card: Is it just a technology name or can reach 1 GigaBit / Second
  • Does computers really reach the maximal network card speed?

Most Important Question (I want to answer):

  • I have a computer that come with a 10 Mbit/sec network card (an old computer of the era of those network cards), is replacing this network card with a Gigbit card a bad or good practice? Will it speed up the data? or will it plant the computer because it's a super card?
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What's the maximum speed of an Ethernet cable (not a phone cable! the one that has 8 threads)

Gigabit Ethernet (1000BASE-T) utilising a standard cat5 ethernet cable is cabable of 1,000 Mbit/s (mega bits per second) or 116 MB/s (mega bytes per second), although achieving this is practice can be troublesome, it's almost possible to achieve using two machines with a crossover cable between two high quality (i.e. Intel) network cards. You can always use multiple network ports/cards in an aggregated or bonded configuration to achieve multiples of this bandwidth (the differences between them are slight, the results differ based on usage - redundancy, throughput, error handling etc).

About the Gigabit Ethernet Network Card: Is it just a technology name or can reach 1 GigaBit / Second

It does what it says on the tin - 1 Gbit = 1,000,000,000 bits, and this is the throughput per second. Notice the difference in Gbits and Gbytes - a factor of 8 (1 byte = 8 bits).

Does computers really reach the maximal network card speed?

This depends on the quality of the network hardware (including the Network Interface Card), intermediate routers, cabling quality, noise/interference from other electrical components (this is unlikely except in the case of very "noisy" components and unshielded cat5) and network load (if you are sharing routers/switches with other devices). You may also want to enable technologies such as Jumbo Frames to increase throughput.

Most Important Question (I want to answer):

Let's assume I have a computer that come with a 10 Mbit/sec network card (an old computer of the era of those network cards), is replacing this network card with a Gigbit card a bad or good practice? Will it speed up the data? or will it plant the computer because it's a super card?

The gigabit card will go faster IF you connect it to gigabit capable equipment (a router/switch or another machine with a gigabit card). As noted by nik you require enough bandwidth on the interface which the card is plugged into (PCI, PCIx etc). The PCI bus has 133.33 MB/s bandwidth and will support the speeds required for gigabit ethernet.

Here is an article Gigabit Ethernet: Is the Time Right? for a business specific implementation.

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  • When measuring throughput don't forget protocol overhead - bits per second on the wire don't translate by dividing them by 8 into bytes of transferred file per second.
    – slovon
    Jul 2, 2009 at 13:35
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  • on 8 wires cat 5e or cat 6 - and up to 100m you'll get gigabit. that's theory - in practice cat 5 works as well.
  • it's not a name - you server can provide and client consume - you can easily saturate gigabit connection and get ~90-95% of throughput on single tcp session.
  • depends... depends if it's cheap gigabit card or something better, depends if source can provide and destination parse / use the data.
  • depends on cpu of old computer, bus-efficiency. i guess you'll replace pci card with pci card. you'll surly get over 100mbit/s [ assuming your cpu is somewhere ~300mhz p2 ], but all depends if you just do http retrieval or sth else.
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The maximum speed of Ethernet connection is 1 Gbit/s. Even in ideal network you won't reach this speed - there is auxilary data in Ethernet protocol, which uses your bandwith.

I don't think that installing 1 Gb card on your old computer is a good idea. Possibly, you have old slow disks and controller on it and the transfer rate will be limited by your system, not network card.

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You will find all your basic answers at the Wikipedia Ethernet page.

If your computer came with a 10Mbps card check its PCI technology where you will plug the card.
It may not support a Gbps card at all.

Finally, if you can and do connect a 1 Gbps network card to your computer, it may typically peak out at 700-800Mbps (even if you use specialized linux kernel modules that avoid data copy in the communication path -- referred usually as zero-copy (2003 article)).

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Because an old 10Mbit/sec network card only transfers data at 1.25MByte/sec (about the speed of old USB 1 flash drives - painfully slow. Even internet connections are faster these days), you can only benefit from upgrading.

100Mbit gives you a 12,5 Mbyte/sec speed, which is still much slower than the standard hard disk these days (maybe about the speed of your old computer).

1Gbit lifts you up to a nice 125 Mbyte/sec, outperforming most hard disks even in raid configuration (especially in writing operations)

The Udma33 interface (about the same time, no ?) had a max speed of 33Mbyte/sec, although you can be sure the disks never reached those speeds.

You can always check this list of common devices for their bandwidths.

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  • It's not exactly a division by eight, it's a bit less each time. 1Gbit is 116 MB/sec.
    – Berzemus
    Jul 2, 2009 at 10:23
  • @Berzemus : false, 1Gbits is 125 MB/S. 1Gbits = 1 000 000 000 bits. 1 000 000 000 / 8 = 125000000 and 125000000 / 1000 / 1000 is 125 MB/s.
    – radius
    Jul 2, 2009 at 10:37
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It depends on what kind of Ethernet cable you are talking about.

CAT5 cable supports up to 100 Mbit CAT6 cable supports up to 1 Giga bit CAT7 cable supports up to 10 Giga bit

Technically a Gig card can transfer data up to 1 Gig per second. However it's tough to actually push that much data though the card.

Technically yes, you could put a faster NIC in an older computer, however odds are the PCI buss (if it even supports PCI) wouldn't be fast enough to support the higher end network card. Assuming that you can get the card into the machine, it may help you transfer the data faster than you currently are, but the odds are that the computer doesn't support moving the data that fast.

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    cat5e (and perhaps cat5) are perfectly capable of running at gigabit speeds. It's cheaper and easier to use than cat6, mostly because the extra shielding makes it harder to bend.
    – David Pashley
    Jul 2, 2009 at 9:03
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    Indeed cat5 will run happily at GBe speed
    – Andy
    Jul 2, 2009 at 9:48
  • This is true, cat5 can happily run GigE without a problem. However if you are walking into a government setup or want something certified for GigE, cat5 isn't going to cut it. It's official rating (unless something is changed which I haven't read which is possible) is that its for 100 Meg. That said, my office is all cat5 running GigE.
    – mrdenny
    Jul 2, 2009 at 18:07

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