Since November, I've noticed in many of my games that multiplayer will have these massive lag spikes that cause my ping to ascend to 500 or so, even while playing with people across the street. The funniest part about it is, I can still watch everyone else move, and I can still voice chat with them. The only thing I can't do is any sort of control (except the menu). The games that I saw this most often were: L4D2, CS:GO, and CoD:WaW.
That went on for a while, I tried many things from disabling my firewall, verifying game cache, I even reinstalled Windows. Nothing helped. My internet connection cannot be the source of the problem as I can still use the internet and voice chat with the other players while having the lag spike. Also, my MacBook Pro can run L4D2 and CS:GO without any problems.
These are my speeds:
Then I looked into the possibility that my network card was glitching somehow. I have a Bigfoot Killer 2100 card. I updated the driver and software, but it didn't help. Then I poked around the hardware to see if anything was amiss. I noticed that I can push the network card farther into the PCI-e slot, but then I cannot screw the card into the casing.
For a while, this got rid of all of the lag spikes. Last week I bought Civilization V. I attempted to play with some friends, but everytime I would join a multiplayer lobby, Steam would crash causing the game to stop responding. So far the only other game to show this is L4D2. Previously I was able to get multiplayer games in Civ V and L4D2 to work, but it was with people playing on my LAN (Civ V has a LAN option, whereas L4D2 does not).
I'm currently at the tradeoff between massive lag spikes or Steam crashes.
NVIDIA GeForce GTX 550Ti 2GB (I have a second one that controls two outer screens, but I cannot use SLI because of motherboard limitations)