Question 1

is this memory UDIMM?

Accepted Answer

Yes, it's unregistered / unbuffered.  Make sure whatever motherboard you're putting this in can use ECC non-registered memory.

Question 2

Will this work with ASUS M2N-E (4 slots, but 8GB max RAM)? Thanks.

Accepted Answer

Check your motherboard info, Google "Asus M2N-E". Newegg won't let me link to the page.

You have a DDR2 board. This is DDR3.

Crucial has a memory compatibility thing on their site you can use. I often use it and order from Newegg anyway.

Question 3

Compatible with Asus P9D-M server motherboard?

Accepted Answer

I would think so because of the chipset > from Crucial :
Guaranteed-compatible upgrades for your ASUS P9D-MH/SAS/10G-DUAL and then they list CT2KIT51272BD160B 
as 1 of 4 pairs. 
2 pair @ 8GB x 2 
and 
2 pair @ 4GB x 2
the only difference between the pairs of 8 or 16 would be 
the voltage - BD = 1.35 & BA = 1.50

Question 4

Compatible with ML310e Gen8 server?

Accepted Answer

Yes, if you google ML310e Gen8 you can find HP's spec sheet.

You see listed in Specifications:
Memory type
DDR3 UDIMM

Showing that it needs DDR3 Unbuffered DIMMs. You have found the correct item!

Question 5

Looking for 8GB memory for intel S1200BTSR server motherboard.. Will this work?

Accepted Answer

I'm going to tell you yes. 
Intel says it tested this piece part # CT51272BA160B @ 4 gb.

Crucial says use this part # CT4856024 only this part# is missing KIT after CT which is usually used to designate that modules have been tested for match.
 
The part Newegg has is listed as CT2KIT51272BD160B - notice the KIT after the CT? 
This part # is identical to the one Intel test with the exception of BA and BD - BA=1.5v and BD=1.3v. 
in the case of memory voltage, less is better.

I believe your board will read the memory and adjust the BIOS accordingly if not you should be able to do it manually. (Don't listen to everything this guys says - 350+ systems in 12 years and not one an Intel board or processor.)

If you have any doubts 
crucial-dot-com-store-mpartspecs.aspx?mtbpoid=9F7984FFA5CA7304
Link to the Curcial Kit - that doesn't say KIT and it's the same price as what Newegg is selling.

But if you bought the board from Newegg ::
I just spent 30 minutes or more  checking specs and running my mouth because Newegg asked for a favor.
Send them an E-mail - tell them if they sell you the board they should have the right parts in stock, at least listed on the websites so they can order them when we buy.

And because there has not been proper ECC Unbuffered in stock for months now -  causing all kinds of headaches for some customers (Like me who has bought nothing else but ECC Unbuffered since 2007) they should get you which ever you chose and give you a $20.00 give card toward your next purchase.

Questions & Answers