I own an Equinox 76. Recently I have upgraded it with a HDD and 2x16MB of volatile ram. Unfortunately I can hear a noticable buzz sound while playing samples loaded to the ram. The more keys I play at the same time (more polyphony used), the louder it gets. There is no such annoying sound when I play the factory (rom) sounds. Is it a known issue or is it a problem with my simm ram?

Thanks in advance