Windows 8.1 Slow Gigabit Networking

I think I'm going mad, my recently reformatted computer (from Windows 7 64bit to Windows 8.1 64bit) will no longer transfer any files to my NAS at more than a 100mbit connection speed.

Whilst on W7 the computer could connect to my NAS and transfer files at 30-50 MB/s (300-500 mbit/s), which was perfect. However now it's on Windows 8.1, the file transfer speed is exactly 11.3 MB/s all the time (100ish mbit/s). I must stress that absolutely NOTHING had physically changed on my network on the day of the reformat and install of Windows 8.1, but you'll see below that I've subsequently replaced a few things to try and find the bottleneck, to no avail!

My current network looks like this:

Asus RT-N66U -> TP-Link Gigabit Switch -> NAS/Computers/Xbox/Raspberry Pi (with Cat6 cables between everything).

My Specs:

• Intel Core i5 2500k (stock clocks)
• 16gb DDR3 Ram
• 256gb SSD and a few multi-TB hard drives.
• MSI P67A-GD53 motherboard
• MSI 560ti Twin Frozr II (stock clocks)
• Windows 8.1 64bit
• Current Network Driver Version: Realtek 8.20.815.2013

List of things that thus far have had no affect:

• Verified nothing is/was using the network besides the NAS and my computer.

• Boot into safemode and reinstalled all drivers one at a time (chipset, nic, gfx, sound etc..). Boot -> Uninstall -> Reboot -> Install -> Reboot (for each driver)

• Verified (and replaced) the CAT6 between each device

• Replaced the TP-Link Gigabit Switch with a new one (had it lying around)

• Configured the cononection within windows and tweaked all the following options (nothing made it better or worse - current settings are in brackets next to each option - after changing each option I would restart the network connection and transfer the same 3gb file from my SSD to the NAS).

  • APR Offload (Enabled)
  • Auto Disable Gigabit (Disabled)
  • Energy Efficient Ethernet (Disabled)
  • Flow Control (Rx & Tx Enabled)
  • Green Ethernet (Disabled)
  • Interrupt Moderation (Enabled)
  • IPv4 Checksum Offload (Rx & Tx Enabled)
  • Jumbo Frame (Disabled)
  • Large Send Offload v2 IPv4 (Enabled)
  • Large Send Offload v2 IPv6 (Enabled)
  • Maximum Number of RSS Queues (4 Queues)
  • NS Offload (Enabled)
  • Priority & VLAN (Priority & VLAN Enabled)
  • Receive Buffers (512)
  • Receive Side Scaling (Enabled)
  • Shutdown Wake-On-Lan (Disabled)
  • Speed & Duplex (1.0 Gbps Full Duplex)
  • TCP Checksum Offload IPv4 (Rx & Tx Enabled)
  • TCP Checksum Offload IPv6 (Rx & Tx Enabled)
  • Transmit Buffers (128)
  • UDP Checksum Offload IPv4 (Rx & Tx Enabled)
  • UDP Checksum Offload IPv6 (Rx & Tx Enabled)
  • Wake on Magic Packet (Enabled)
  • Wake on pattern match (Enabled)
  • WOL & Shutdown Link Speed (10 Mbps)

I'm at a loss, I don't know what to do next besides reinstalling Windows 7 again (I'm not averse to this, but I'd rather adopt Windows 8). Does anyone have any final suggestions?

If I have forgot to provide any details, let me know.

I recently had a similar problem with my configuration: Upgraded from Windows 7 to 8.1 with the following new hardware:

• Asus 990fx Sabertooth (latest drivers)
• AMD 8350 CPU Buffalo
• Terastation live NAS box computer<-->NAS connected via a 100/1000 5 port unmanaged switch

I was getting periodic timeouts to the NAS. When I set a continuous ping from the computer to the NAS it would drops pings every few seconds. I suspect I have a similar NIC configuration to yours. I disabled many of the parameters you listed above but the timeouts only disappeared after I updated the Flow Control (Rx & Tx to DISABLED)

BTW I'm not sure many of those offload functions are useful and I've seen from a work perspective them causing problems on a network. The problem lies in the OS not cleanly offloading the respective functions when returning/going to sleep. Anyway, hope this helps. Dave