Device overheating message

, 2013/06/11 09:46

Hi, I'm running my FPGA 1.15b + experimental board 1.3.

As soon as I start the BTCMiner, I'm getting the following error:

2013-06-10T19:31:43: ztex_ufm1_15b1-04A39E20AD: New device: bitfile=ztex_ufm1_15b1 f_default=184.00MHz f_max=224.00MHz HpC=0.5H

2013-06-10T19:31:43: ztex_ufm1_15b1-04A39E20AD: MAC address: 0004a39e20ad

2013-06-10T19:31:43: ztex_ufm1_15b1-04A39E20AD: FPGA 1: configuration time: 235 ms

2013-06-10T19:31:44: ztex_ufm1_15b1-04A39E20AD-1: New FPGA

2013-06-10T19:31:44: ztex_ufm1_15b1-04A39E20AD-1: Set frequency to 184.00MHz

2013-06-10T19:31:44: ztex_ufm1_15b1-04A39E20AD-1: Using LongPolling URL http://mint.bitminter.com:8332/lp

2013-06-10T19:31:46: ztex_ufm1_15b1-04A39E20AD-1: Set frequency from 184.00MHz to 176.00MHz

2013-06-10T19:31:48: ztex_ufm1_15b1-04A39E20AD-1: Set frequency from 176.00MHz to 184.00MHz

2013-06-10T19:31:51: ztex_ufm1_15b1-04A39E20AD-1: Set frequency from 184.00MHz to 176.00MHz

2013-06-10T19:31:54: ztex_ufm1_15b1-04A39E20AD-1: Set frequency from 176.00MHz to 168.00MHz

2013-06-10T19:31:54: ztex_ufm1_15b1-04A39E20AD-1: Error: Hash rate drop of 8.7% detect. This may be caused by overheating. FPGA is shut down to prevent damage.: Disabling device

What are the possible causes? As power supply I'm using this one from Conrad http://www.conrad.de/ce/de/product/512898/VOLTCRAFT-FTPS-12-60W-Tischnetzteil-Getaktet-Schaltnetzteil-12-VDC-5000-mA-60-Watt?queryFromSuggest=true

~~DISCUSSION~~