A strange noise

My soon to be wife has a HP computer that is only a few years old. She has Vista on it, the same as mine, and it is making a strange noise at times. It seems to get more noisy if we talk. Well let me describe it to you, before I go on and lose you. The sound it is making is like the sound you get when you put a card on a bike wheel, but not that loud. It happens rarer now, but before we moved it made it a lot. So anyway now it makes it only a little, or rather not that often, but when it is making the noise it gets worse as we talk, or make noises our selves it gets faster, so it is weird. I have no idea what is wrong with it and it is driving me nuts to figure it out. There is no performance problems so we don't think it is the hard drive, so what could it be?

Hi 1 Have a look at any fans that are visible..press gently on the case near to the fan when the machine making a noise….. does the noise alter? 2 Do you have a sound system on the computer? 3 does altering the volume setting change the volume of the strange noise? 4 Do you have a microphone in your computer? ( they are usually built in to laptops, but not desktop models unless added after wards) 5 Are you familiar with acoustic feedback principles? 6 Does the sound alter when you play a music CDROM? 7 Are you familiar with the sounds a hard drive makes when it spins up? 8 Ditto for a CD/DVD drive? 9 Feel carefully all over the machine when the weird noise is sounding off…any strange vibrations detected? 10 Have you carried out a virus/malware check with your updated anti virus product and also an on line scan? (Kaspersky or Eset for example?) 11 Do you use Internet Radio? 12 Disconnect all peripherals from the machine, if its a laptop remove the battery, just have the mains supply via the voltage dropper connected, emprty all optical drives, remove all scanners, printers I pods, flash drives etc ( unplug them all) so you are running on "bare bones only" any changes noticed in the weird noises? ( if its a desktop machine then just have the mains power cable the Video cable mouse and keyboard connected unplug everything else…any changes in the noise? hopefully some of the questions above may lead you to things that you should check, but when you post back with the answers, please provide the make and model number of the computer, and we will do our best to advise further. Regards paws