Samer1970 :
wow , I did not know that some i3 have ECC support. but there is still a problem , the Chipset must support ECC as well...
True. You must buy a workstation/server board, even though the CPU is just an i3. This makes it still rather pricey.
I think the main reason for it is that there aren't really dual-core E3 Xeons. So, for those not needing 4 cores, the low-end is served by the Pentium line, while the high-end is served by the i3 line.
Samer1970 :
but still why is intel doing this ? Just make ECC standard option and move on ...
I wish they would, but they'd rather play market segmentation games. There's not much else separating desktop CPUs from E3 Xeons.
The situation was simpler when the memory controller was in the chipset, as I was able to use ECC RAM on my old Pentium 4 system by simply getting a montherboard that supported it.
Samer1970 :
What do you mean by 1 DIMM per channel ?
Exactly that. Mainstream desktop CPUs have 2 memory channels for achieving twice the bandwidth of what a single channel would enable. When you move up to Extreme desktop and E5/E7 Xeon CPUs, they add two more channels, doubling bandwidth again. On a quad-channel CPU, the optimal way to populated memory is with one unbuffered DIMM per channel (i.e. 4 DIMMs, total). Anything more - registered or 2 DIMMs per channel will add latency or reduce clock speed.
Check the links you posted. On of the specs they list is the maximum number of memory channels.
Compare with this Extreme desktop CPU, which shares the same socket as the E5/E7 Xeons:
http://ark.intel.com/products/94189/Intel-Core-i7-6800K-Processor-15M-Cache-up-to-3_60-GHz
To feed more cores, you need more memory bandwidth.