Guys, This is a new one on me. I have been using the onboard LAN (RTL-8139/8139C/8139C+ (rev 10)) for several years and always got great transfer rates: 01:0b.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+ (rev 10) Subsystem: Giga-byte Technology GA-7VM400M/7VT600 Motherboard Flags: bus master, medium devsel, latency 32, IRQ 16 I/O ports at 8000 [size=256] Memory at e8000000 (32-bit, non-prefetchable) [size=256] Capabilities: [50] Power Management version 2 Kernel driver in use: 8139too Kernel modules: 8139too, 8139cp 10:02 providence:~/arch/pkg/new-110718/virtualbox_bin> rsync -uav --progress virtualbox_bin-4.0.12-1-i686.pkg.tar.xz phoenix:/srv/http/dl/arch/i686 sending incremental file list virtualbox_bin-4.0.12-1-i686.pkg.tar.xz 55685508 100% 11.59MB/s 0:00:04 (xfer#1, to-check=0/1) sent 55692427 bytes received 31 bytes 10125901.45 bytes/sec total size is 55685508 speedup is 1.00 I was having intermittent lockups during large file transfers (memtest is fine), so I thought I would change the NIC. I installed a 3Com Corporation 3c595 100BaseTX [Vortex] card and tested the throughput. The throughput is 1/3 what I was getting with the Realtek card: 01:07.0 Ethernet controller: 3Com Corporation 3c595 100BaseTX [Vortex] Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx- Status: Cap- 66MHz- UDF- FastB2B- ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx- Latency: 248 (750ns min, 2000ns max) Interrupt: pin A routed to IRQ 19 Region 0: I/O ports at 8000 [size=32] [virtual] Expansion ROM at 80000000 [disabled] [size=64K] Kernel driver in use: 3c59x Kernel modules: 3c59x 12:47 providence:~/arch/pkg/new-110718/virtualbox_bin> rsync -uav --progress virtualbox_bin-4.0.12-1-i686.pkg.tar.xz phoenix:~/tmp sending incremental file list virtualbox_bin-4.0.12-1-i686.pkg.tar.xz 55685508 100% 3.27MB/s 0:00:16 (xfer#1, to-check=0/1) sent 55692427 bytes received 31 bytes 3182426.17 bytes/sec total size is 55685508 speedup is 1.00 I searched the forums and I've tried ethtool in setting speed, duplex and autoneg, but it makes no difference. i.e.: ethtool -s eth0 speed 100 duplex full autoneg off What else can I try to get this card working correctly? All light indications on the card and the switch it is connected to show a 100TX connection is being made. What say the gurus? -- David C. Rankin, J.D.,P.E.