CPU noises leaking into HD cards

[oliarnalds]

This problem weirdly started only yesterday, while i've had the computer for a couple of weeks...

I'm sure you've heard this sound before - the little digital noises and crackles that CPUs make, and i remember when i was a kid this would often be leaking into the headphone output on my PC computer... But now it's somehow leaking through my HD cards and into my monitors.

I have tried different monitors (active Adams vs inactive NS10 with amp in a different socket) to rule out that it has something to do with the electricity.
I have tried removing USB devices and and hard drives.

Anyone got any other tips?

My computer is a PC running MacOS 10.6.6
Intel i5, 2.81Ghz Quad Core
Motherboard: Intel 1156, Asus.
8gb DDR3 RAM 1333 MHz
HD2 PCIe, Pro Tools 9.0.2

[Noiselab]

You've probably already checked this, but it bears re-checking.

I had a problem like this years ago with an AudioMedia II card in a Mac IIcx (yes, that long ago!). The problem turned out to be a ground loop caused by comparatively different paths to ground between the computer and the powered downstream audio devices. The Mac IIcx was plugged into one outlet, and the amp and mixer were plugged into another. Doh!

Mine was an exasperating lesson, but it's made me VERY careful now about power and ground circuit management.

I've since seen similar things in others project studios caused by old power strips with bad ground prong contacts. Or, in one case, a video monitor plugged into a different outlet. To test, you can try a ground lift adapter on the PC or other down-stream devices - but I do not recommend running that way permanently.

Hope it's that simple!

NL

[oliarnalds]

Sadly it's not that simple i've ruled that out...

The problem even goes away sometimes.. i was noise free for a couple of hours today, but now it's back.

[DigiTechSupt]

I've seen this before and it's almost always been related to a bad component, card or motherboard. Cables connecting things inside the computer could be the culprit as well.

Unfortunately there's no quick and easy solution other than replacing/removing components/cables one by one until you find the one that's causing the problem. If it's a bad motherboard you'll eventually find that by having replaced/removed other components until the motherboard is the only thing left to test.

[Noiselab]

I think DTS is on the right track.

Just to clarify, are you saying that it comes and goes without any power or audio re-wiring/routing of any sort?

If so, that sounds like it's likely to be an intermittent ground-fault somewhere inside your PC. If you're comfortable with it, you might try gently wiggling all the main harness connectors inside the PC (with the power turned off of course) to see if you can make a difference. It's an ugly method, but it may be your only option. The usual offenders tend to be drive connectors (stepper motors can throw voltage noise back onto the source line if not appropriately isolated in the circuit), but YMMV. Besides external ground faults and loops, squiffy internal connections are the most likely candidates for intermittent issues like you're describing.

At worst case, it might be a cold-solder joint somewhere in your PC. Both squiffy harness connections and cold-solder joints can be affected by temp/humidity changes and/or whether you brushed your teeth effectively this morning...

Hope that helps!

NL

[oliarnalds]

Thanks a lot guys! This helps a lot! I guess i may have accidentally done something bad when i have been messing around with the HD cards...

Originally Posted by Noiselab

Just to clarify, are you saying that it comes and goes without any power or audio re-wiring/routing of any sort?

Yes, but on second thought i don't think it ever really goes away completely, it's just quieter - maybe when whatever component is causing the problem is in less use.

I will try wiggling around with different components inside the computer and see if something helps. Can't say i'm super comfortable with it though! - I wish i could have the computer shop do it, but i guess they have no way to check if it fixed or not... :s

[Craig F]

is it in the recording or just the monitor chain?

I had a G4 that would make digital noises when the mouse was moved