Ping lag and stutter UPDATE Still need help!

i5, 8GB Ram, R9 290, Win8.1

While playing TTT, I get a stutter every 10-20 seconds making it difficult to play.
Using the net graph, you can see the ping spike (lowest red bars)eg.

I have another machine and this problem does not occur there(same network)

I tried;
validating files, steam said 2 failed and downloaded them
moving from a HDD to a SDD
quitting the wireless adapter software
checked Windows Firewall
switching server
switching gamemode
disabling addons

Any ideas of what could be causing the problem would be greatly appreciated

Reinstalled Gmod, issue is still there
Ran Gmod in Safe mode with Networking, no ping lag
This leads to believe a different program/s is causing
Any help on how to identify this program???

Also happening with tf2

Could possibly be the cpu/graphics card overheating or failing. Do you happen to have any others lying around or have a friend that can spare you one or the other for testing?

Sorry, completely forget about this thread after fixing the problem!
I used a power line adapter to connect to Ethernet and the issue is gone
Thanks for the help though