VIAVI TestCenter: what might be causing FCS errors when using LR8 in a PX3/DX3-QSFP-DD-2 (PX3/DX3-400G-T2)?

VIAVI TestCenter: what might be causing FCS errors when using LR8 in a PX3/DX3-QSFP-DD-2 (PX3/DX3-400G-T2)?

• The retaining spring wire that holds the heat sink to the transceiver cage looks like it broke. • Port 1 (which is seeing FCS errors): • This is what the failure looks like. • The spring wire that helps hold the heat sink against the transceiver cage came off. You can see it drooping from top-right to bottom-left.  • The result is that the transceiver became very hot (apparently one of the transceiver's registers reported that it was at 90 C° / 194 F°) leading to the FCS errors. As examples of transceivers' operating temperatures: • Finisar FTCD1323E1PCL: operating temperatureis from 0-70 C° • per ColorChip's roadmap: operating temperatureis from 0-70 C°  • Note: in this picture, the right is the front of the card as shot from the left side of it, looking from the front. • Port 2 (this port is not seeing FCS errors) • This is what the spring wire should look like. • Notice that there is no slack in the spring wire. • Note: in this picture, the left is the front of the card as shot from the right side of it, looking from the front.