First of all let me tell you that for this particular processor that you describe there 2 versions E5-2403 and E5-2403 v2. In the following URL you will find all the compatible server boards and chassis for E5-2403
and for E5-2403 v2:
Just for you to consider pretty much all the compatible boards and chassis are end of life now and will be difficult to find one from an authorized reseller. In case you find one from a 3rd party reseller most likely it will be out of warranty.
Hope this helps.
There are different ways to find it out depending if you have the processor physically in front of you or if you have it installed and running on a system.
If you have it physically in your hands you can follow this article, http://www.intel.com/content/www/us/en/support/processors/000005965.html
If the processor is currently installed and running on a system you could access the BIOS (F2 during POST) > Processor.
If running any Windows OS go to Device Manager > Processor, if running Linux try the /proc/cpuinfo command
Below is the information i get from cat /proc/cpuinfo
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 45
model name : Intel(R) Xeon(R) CPU E5-2403 0 @ 1.80GHz
stepping : 7
microcode : 0x710
cpu MHz : 1199.953
cache size : 10240 KB
physical id : 0
siblings : 4
core id : 0
cpu cores : 4
apicid : 0
initial apicid : 0
fpu : yes
fpu_exception : yes
cpuid level : 13
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx lahf_lm arat epb pln pts dtherm tpr_shadow vnmi flexpriority ept vpid xsaveopt
bogomips : 3600.09
clflush size : 64
cache_alignment : 64
address sizes : 46 bits physical, 48 bits virtual
May i say that is E5-2403 v1 ?
Frankly speaking, my current board for the processor is Asus Z9NA-D6 but i found theres a lot of problem on the controller and compatiblity, that why to not wasting my processor, RAM and casing, i plan to buy a new board were support the processor and RAM, i search around and i found theres an offer for the Intel board S2400EP4, based on the dimension is it compatible to replace my Z9NA-D6?
Please help. TQ
Thank you for the information and it looks like it is a V1.
If there is anything else we can help please feel free to ask.