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Onboard NIC performance hits?

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September 25, 2006 8:35:45 PM

Im bascially wondering if there would be any performace hits/bennitfits for using an onboard NIC over using a PCI NIC?

also, are there any bennifits in using a PCI-E x1 NIC over a standar PCI nic?
September 28, 2006 12:35:51 AM

Quote:
Im bascially wondering if there would be any performace hits/bennitfits for using an onboard NIC over using a PCI NIC?

also, are there any bennifits in using a PCI-E x1 NIC over a standar PCI nic?


Two part question then (a) on-board vs. PCI add-on. (b) PCI add-on vs. PCIe add-on.

All else equal, PCIe add-on or good on-board are better.

Good on-board could be PCIe or better. But on-board could be bridged via PCI (I'd call this "not so good" on-board). The chipset could be good, or not so good. You can't just look at these factors in isolation -- one PCI add-on NIC could be better than another on-board or PCIe NIC in one situation for factors not related to the interface.

In general, if you can stay away from crowding the PCI bus, that's better. You'll want a fast network card pretty much for transferring a lot of data among computers in a local network, and this will pretty much mean hitting the drives pretty heavily. The worst config you can do here is to use a PCI add-on NIC and a PCI storage controller on the same bus. You can get by with an on-board or PCIe NIC and a PCI storage controller, so it's better to avoid a PCI NIC if possible.

However, in many cases the performance difference between a good and bad GbE NIC, and a PCI and PCIe GbE NIC are going to be higher than what your drives are capable of, so just won't matter much to you. This is the typical case, with transfers hitting around 30 MB/s. In this case, any old GbE NIC is much better than even the best 10/100 NIC, and not really worse than the very best GbE NIC in practice (because you're limited by the drives, etc., not the NIC).

In my experience, you can mitigate to a significant degree the performance loss seen with PCI NICs by using jumbo frames, for which you need a JF-capable switch and JF-capable NIC on the other side. However, if you start with a good on-board NIC or a PCIe NIC, then there's not much to gain other than some potential CPU utilization decrease for the trouble of jumbo frames.

Now, for a simple single suggestion, a lot of people recommend Intel NICs, and Intel has a PCIe version that's not incredibly expensive -- the Pro 1000 PT. This should be a safe general recommendation that avoids a lot of complexity for some cost. However I haven't used one yet; I've found good performance with on-board and PCIe NICs, and decent performance with an Intel Pro 1000 MT PCI with jumbo frames enabled.

http://www.hardforum.com/showthread.php?t=1103452
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September 28, 2006 4:24:24 AM

thanks for the great info...

what i had gathered from the anandtech forums was basically: "no not really" ...

most onboard NICs seem to be pretty good to me, as they seem to give me the speeds i like/am capable of getting...

i asked about the PCIe mainly because there are only 2 PCI slots on my motherboard, and ill be wanting a soundcard sometme (as adding one of those i hear is one of the best ways to free CPU... things (sorry its late) ... and since those pci slots are side-by-side, i dont really want to put more than 1 thing in em at a time...

thanks again for all the info though
September 28, 2006 11:54:41 PM

Quote:
since those pci slots are side-by-side, i dont really want to put more than 1 thing in em at a time...


Why would you think this? That is someting I would not worry about.
September 29, 2006 2:35:01 PM

well i had heared that putting in a lot of pci cards side by side can sometimes get some interference (i think on the bus or somethin?)... im not too worried about it ether, but i'd much rather use my pcie than pci...
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