Whats the difference between these two RAM chips?

[AlmightyG5]

I went to newegg to check out there RAM for my iMac and i found this:http://www.newegg.com/Product/Product.asp?Item=N82E16820146532

So i take the module number of the crucial chip from newegg and search for it at the crucial site, and i get this:non-Mac crucial chip (http://www.crucial.com/store/partspecs.asp?imodule=CT6464Z40B&WSMD=CT6464Z40B&WSPN=CT6464Z40B)

Then i use the crucial RAM finder and select my iMac and I get this:iMac RAM crucial chip (http://www.crucial.com/store/MPartspecs.Asp?mtbpoid=54B01A99A5CA7304&WSMD=iMac+%28G5%2D2%2E0GHz%2C+17%2Dinch%29&WSPN=CT440181)

There is no difference between the two modules other than under the speed catagory which says that the iMac RAM crucial chip (http://www.crucial.com/store/MPartspecs.Asp?mtbpoid=54B01A99A5CA7304&WSMD=iMac+%28G5%2D2%2E0GHz%2C+17%2Dinch%29&WSPN=CT440181) has a speed of "400" and the non-Mac crucial chip (http://www.crucial.com/store/partspecs.asp?imodule=CT6464Z40B&WSMD=CT6464Z40B&WSPN=CT6464Z40B) has a speed of "DDR 400". That is the only difference between the two, correct? So would that first chip from newegg with a speed of "DDr 400" work with the iMac? Because it is 20 dollars cheaper.

[CanadaRAM]

There is no difference in the specs that you can read, however those are not the only specs.

A critical specification for the iMac is the setting of the Serial Presence Detect chip. If the SPD values are wrong, then the Mac will reject the module. When you purchase the Mac part from Crucial, they are guaranteeing that the SPD and all other settings are correct for the iMac. When you buy the generic chip, it may or may not have the correct SPD settings and NewEgg makes no claim of compatibility.

If you are in the USA, for $52 you can get a compatibility guaranteed module here: Data Memory Systems (http://www.datamem.com/viewcat.asp_Q_C_E_1158)

So if you want to take a chance on NewEgg at $41.17, you can try it. Worst case is you'll be out the shipping 2 ways and possibly a 15% restocking charge.

"There is a restocking fee of 15% on all returns for refund (RMA Refund), unless waived by a Customer Support Agent. We charge this 15% restocking fee for all returns for refund to encourage customers to purchase products they intend to keep. We offer RMA Replacement without any restocking fee to support customers who have received a defective product. For CPU and Memory refunds, any restocking fee we use will be a reflection on current market value for the same cpu item. Newegg.com does not pay the return shipping cost for defective merchandise. We are not responsible for product defects, because we do not manufacture the products we carry. However..if you pay to send the item back to Newegg.com, Newegg.com will replace the item and ship the item to you at no charge. "