You originally indicated that you had memory 4 x 8Gb Kingston KVR24E17S8/8 modules which are unbuffered. Otherwise, try to drain the system flea power by shutting down the server, disconnecting AC power cables and then press and hold the power button for about 15 seconds. Reboot the server and see whether it successfully POSTs.
The same thing is using only one memory module, unable to enter BIOS. Moving NVRAM jumper from 2-3 to 1-2 position also gives nothing.
To clear the NVRAM, power down the server, move the NVRAM_CLR jumper cables from 3-5 to 1-3 position and reboot. Wait about 5 minutes, power down the server and then move them back to the default position 3-5 and reboot. See page 220 of the Users' Guide for more information: http://topics-cdn.dell.com/pdf/poweredge-t430_Owner's%20Manual_en-us.pdf