We have 7 servers R710 in our datacenter. From two of them we receive sometimes not regulary alert emails about power supply failure. But it takes only a second and is OK again immediately. Sometimes it is power supply 1, sometimes power supply 2. We tried to change cables already but no difference. I tried to update idrac firmware to newest version - no difference.

These two servers are the oldest which we have. 

Could it be problem with some sensor or what is the problem?

I greatly appreciate any help. 

Thanks.

Log:

Sun Jul 22 2012 18:23:12 The power supplies are redundant.
Sun Jul 22 2012 18:23:11 Power supply 2 is operating normally.
Sun Jul 22 2012 18:23:07 Power supply redundancy is lost.
Sun Jul 22 2012 18:23:06 Power supply 2 failed.
Sun Jul 22 2012 18:23:05 Communications are restored for power supply 2.
Sun Jul 22 2012 18:23:05 Can not communicate with power supply 2. 

Sun Jul 22 2012 01:24:03 Power supply 1 is operating normally.
Sun Jul 22 2012 01:24:02 The power supplies are redundant.
Sun Jul 22 2012 01:23:58 Power supply 1 failed.
Sun Jul 22 2012 01:23:57 Power supply redundancy is lost.
Sun Jul 22 2012 01:23:54 Communications are restored for power supply 1.
Sun Jul 22 2012 01:23:54 Can not communicate with power supply 1.