I have a PNY Verto GeForce 4 Ti 4200 with 64 MB. I was doing some overclocking with the card yesterday. I changed the stock speed of 250/514 to 275/570. Everything was running fine. Now today I turned the computer on and I heard a low humming sound coming from the case. So I turned off the comp immediately and opened it up. I took out the video card and reseated it in the AGP slot. I then started it up again and it gave me the same sound. I let the computer sit for 1 hour and then turned it on. Now everything is fine, and there is no humming sound. All the speeds on the FSB and the card are back to stock. I only overclock when I am benchmarking. Is it possible that I did damage to the card? The screen looks fine, and there is NO flickering on the screen. Is the card OK?