x1 PCI Express System Timer

http://www.amfeltec.com/products/x1pcie-system-timer.php

The x1 PCI Express System Timer uses a hardware clock to synchronize IP signals. This hardware-based solution provides accurate clock timing for Asterisk Open Source PBX software.

The Timer supports variable clock timing intervals. You can configure the clock interval during startup. Currently, the x1 PCI Express System Timer supports clock intervals ranging from 1ms to 64ms.

The x1 PCI Express System Timer is retained inside a computer chassis by using the unique PCI Express add-in board retainer (US Patent 7,850,475). The Retainer securely holds the x1 PCI Express System Timer and prevents the Timer from wiggling without using a bracket.