On a breadboard that hash could be coming from*anywhere*. AC couple VIN and up the gain and see if there's anything clearly periodic there from the PSU you can trigger on, then if so have the DAC output a steady 2V (midrange) and see if the noise on the output correlates with the PSU noise.
I guess this thread is moving away from the original question...
There doesn't seem to be any noise coming from the 9V DC adapter I was using because the noise was the same when using a 9V battery instead.
last night it was either around 70kHz and then around 140kHz.
I noticed that it got much worse if I pushed the cable of the probe closer to my computer. Tonight I brought the scope upstairs where there's noting but a clock plugged into any outlet and I still found some spikes at the same frequency when looking at the Wavegen output set to DC or at the top of the square wave from the Probe Comp output.
The random part of the noise is definitely much less I use the little spring ground probe instead of the regular hook and ground wire with the alligator clip.
I guess the only other thing I can check is to plug it in at someone else's house to see if it's something to do with the electricity in this house. I've tried three different probes and they give me the same results.
I never thought about anything until you mentioned it. I've never used a digital scope before winning this DSOX1102G and I don't think I've bothered looking at a signal while set at 10mV/div.
What could there maybe be in the scope itself that causes spikes at 140 or 70 kHz?
Here's an image of just sitting the probe on the desk with the grabber and ground clip connected to exaggerate the periodic signal and another image with the accessories removed.
If I put my hand very close to the tip without touching it I can see the spikes again but when I move away I can't trigger on them.