It is not compatible: Dell-supported processors for PowerEdge 840: Single Quad-Core Intel® Xeon® 3200 seriesSingle Dual-Core Intel® Xeon® X3200 series*Single Dual-Core Intel® Xeon® 3000 seriesSingle Intel® Core™ 2 Duo E4000 seriesSingle Intel® Pentium® Dual-Core 2100 seriesSingle Intel® Celeron® 430, 1.8GHz, 800MHz front side bus, 512K cacheSingle Intel® Core™ 2 Duo E4700Single Intel® Pentium® Dual-Core 2220 Single Intel® Celeron 1200 * The PE840 system launched before type "II" is not supported with Xeon CPU X3200 series. Intel supported processors for the Intel 3000 Chipset: Intel® Celeron® Processor 420 (512K Cache, 1.60 GHz, 800 MHz FSB)Intel® Celeron® Processor 430 (512K Cache, 1.80 GHz, 800 MHz FSB)Intel® Celeron® Processor 440 (512K Cache, 2.00 GHz, 800 MHz FSB)Intel® Celeron® Processor 450 (512K Cache, 2.20 GHz, 800 MHz FSB)Intel® Core™2 Duo Processor E4300 (2M Cache, 1.80 GHz, 800 MHz FSB)Intel® Core™2 Duo Processor E6400 (2M Cache, 2.13 GHz, 1066 MHz FSB)Intel® Xeon® Processor 3040 (2M Cache, 1.86 GHz, 1066 MHz FSB)Intel® Xeon® Processor 3050 (2M Cache, 2.13 GHz, 1066 MHz FSB)Intel® Xeon® Processor 3060 (4M Cache, 2.40 GHz, 1066 MHz FSB)Intel® Xeon® Processor 3070 (4M Cache, 2.66 GHz, 1066 MHz FSB)Intel® Xeon® Processor X3230 (8M Cache, 2.66 GHz, 1066 MHz FSB)Intel® Xeon® Processor X3210 (8M Cache, 2.13 GHz, 1066 MHz FSB)Intel® Xeon® Processor X3220 (8M Cache, 2.40 GHz, 1066 MHz FSB)  
Hey Guys, I have a Dell PowerEdge 840, that I've got from a friend. It currently has a Pentium D (2.80GHz) processor, running on A02 BIOS. I have a spare Dual Core E8500 CPU that I want to use in this server. I have tried to do a direct swap and the server doesn't post after the swap, nor does it give out an error with beeps or lights, except that both the HDD and CPU led's were lit constantly. So my question is then, Is this processor not compatible with the server? Anyone have any experience with it? Thanks for the help in advanced.
PowerEdge 840 Cpu Upgrade