I need help with a weird Networking issue!

[Toxsickcity]

Okay to start I am not a noobie when it comes to PC hardware... but I am seriously having a problem I cannot seem to fix no matter what i do..

It happens with many PC's I own..

The current one is a VISTA BOX

Okay to start I have the problem of VERY Slow SPEED for file transfer accross a network.. usually transfering at a rate of 60-200KB/sec

@ 100MB Full Duplex file transfer to Vista box is about 60KB/Sec-700KB/sec going fast slow etc..
@ 10MB Full/Half Duplex the transfer is 1.2MB/SEC constant! very fast compared to what I get with 100MB...

heres the thing when I send a large file VISTA BOX --> SERVER at any speed it goes at the fastest possible speed! 10MB = 1.2MB/sec | 100MB = 9.8MB/sec
also if I transfer the file from the SERVER or my system to the VISTA BOX is transfer at about 3.5-8MB/sec but my system is very busy!

I've tried different Switches, my main Switch is a 3COM 8port gigabit switch model 3C1670800A

I've tried the SERVER & the VISTA Box in my Internet's Router 4 port'ed switch same problem keeps happening

I Have also checked cables and changed many cables to test things.

I do not have a domain, and my usual network setup is to use static Ip's for each box.. eg: 192.168.0.1, 192.168.0.2, 192.168.0.33 etc...

I have had problems with mainly onboard NICs, and usually fixed by Buying a PCI NIC but I got a new NIC today and same f'en problem.

Computers I've usually and always had problems with
N-Force 2 Asus A7N8X-X with AMD MP 2800+
and a ASrock 775i65GV cheapo mobo 2.66GHZ Pentium 4 775

My other Pc's that are working 100% absolutly no problems in my Network are following PCs..
1. Core2 E6400 with a Gigabyte DQ6 high end MOBO
2. AMD 3800X2 with a DFI lanparty NF4 sli high end mobo
3. SERVER = 8KNXP with a 2.4G Pentium4
4. HTPC 1 = Pentium4 3ghz and Gigabyte mobo unknown model forget!!
5. HTPC 2 = Pentium4 3GHZ and a Gigabyte mobo unknown model

so thats 7 PC's connected and only 1 of them with a problem..

My work had a problem but I fixed that with adding a new PCI N/W card.
any ideas of what I can do to fix this issue?

 

[Nodsu]

heres the thing when I send a large file VISTA BOX --> SERVER at any speed it goes at the fastest possible speed! 10MB = 1.2MB/sec | 100MB = 9.8MB/sec
also if I transfer the file from the SERVER or my system to the VISTA BOX is transfer at about 3.5-8MB/sec but my system is very busy!

So what is the problem?

Do you have any firewall, antivirus, VPN, packet capturing software installed? Uninstall these one-by-one. Also, did you change the network cards on both the involved computers?

It could be that something is flooding your network. Connect the computers with a crossover cable and use some network monitor utility to make sure that only the file copying occurs and nothing else is moving acros the network.

 

[DelJo63]

check your MTU size. I set mine to 1496 to avoid FRAGMENTED packets.
If a packet gets fragmented, then the system needs to reassemble it when it arrives.

This is especially helpful when a firewall disables FRAGMENTS (for security reasons).