Question : Problem: On-board Gigabit LAN - Are they really GB ?

I have never really used onboard LAN for servers, always insist on using PCI-X 64bit cards to ensure correct performance, now PCI-X is slowly going out of fashion, the next step is PCI-e, ones I use most are the Intel PRO/1000P pn PCI-e X1 slots, performance on these seems to be fine, but I am wondering the following :

Onboard LAN such as ones thats included on most motherboards (ie.Abit, Asus) , are they really Gigabit or just a name but run on PCI bus speed ?
Are the Dell/HP broadcom onboard LAN true GB ?
I have also tried 33bit PCI Gigabit cards (ie. Realtek 8169 chipsets), but due to the limitation of PCI bus, they are nowhere near the GB speed, how can the manufactures still markets them as Gigabit products ?

Thanks

Answer : Problem: On-board Gigabit LAN - Are they really GB ?

This very much depends on the chip set used on the mother board.

I have had a few different mother board with different network cards built on. and some come close to GIG standered other fall well short. However i have noticed one thing. When running a "cheap" NIC (which is what most mother board cards are!) at full speed for an extended period of time. the always seem to fall over or frease up at some point!

And when talking to the developers of the network monitering tools i use (Observer from network instruments) I was told this is a common problem. mainly caused by cheep NIC's off loading a lot of the work to the system CPU, and having cheaper memory and components. where as more expensive NIC do more work on board and have much better memory buffers and error handeling etc etc.

So although a cheep NIC may well work ok on a client machine where it will still reach GIG speed. but wont be subjected to heavey loads for long periods. They are not a good Idea on Servers which may be expected to run at near full load 24/7.

It really is a case of get what you pay for. there is a reson a NIC may only cost £5. and another costs £250. and to keep most MB prices down most manafacturs go for ones closer to £5 than £250. However they both should meet gig standered! They can all recive data at gig speeds. but as soon as there buffers are full they have to slow down. and as many have very small buffers they dont mange to keep it up for long ;) espical as a 33bit PCI bus can only ferry data to the system at about 133MB/sec. But is is still usfull as it means a server on a true 1GB/sec link can send small amount of data at gig speeds to many clients in a short space of time. so although they can't keep up the throuput on the client in theroy a servor can still send more data to more clients in the same amount of time.