Mid 2007 iMac Loses WiFi Signal w/ Ext Monitor Connected

[dh.greece]

I have Mid 2007 iMac that works well by itself but when I hook up an external monitor, things get a bit weird. The machine really still performs well, but after about 5 minutes, it drops WiFi signal completely. Again, everything else seems to be functioning normally.

My thoughts were that since it is an old machine that maybe the Power Supply is a bit weak and can't run the extra monitor?!

Any ideas, let me know.

Specs Below:
Mid 2007 iMac 20"
2.4GHz Core 2 Duo
4 GB 667MHz DDR2 SDRAM
ATi Radeon HD 2600 Pro 256Mb
OSX 10.8.2 Mt Lion

 

[bmcgrath]

What's the external monitor?

 

[dh.greece]

The external monitor is a Dell 20", Model # B9H.

 

[dh.greece]

The external monitor is a Dell 20", Model # B9H.

I've tried the monitor on PC's and it does not cause a problem. On occasion I am also having low power warnings when I use the wired keyboard USB slots.

Any ideas?