Originally Posted by eXXon
Unless I'm reading it wrong, DDR4 at much higher speeds is 10% slower than DDR3 at lower speeds......How is that possible?
Timings and a well-developed Bios might help a bit, and then what? DDR4 will be almost as fast as DDR3 (that has a lower frequency).....
....Again, how is that possible ?
& cheers M for all the info. +rep up the wazoo.
The performance of ram is based both on speed/bandwidth and latency. CAS is the delay
between imc presenting a column address and receiving the data. This is simplification to point of error, but to illustrate a point ... say 2666 megatransfers per second (per cycle) is 30% faster than 1866 megatransfer per second providing the delay between cycles is the same. However if one has a 40% larger delay per cycle because of slow CAS, then not surprising for 30% faster speed per cycle to be slower in performance because of the huge delay between cycles. 2666 should be CAS 11 or 10, 2666 CAS 15 is slow.Anandtech
has a good article on comparing RAM speeds based on speed/timings, and some quick and dirty means for comparison. And although you cant directly compare ddr3 and ddr4 because of architectural differences, these differences are not miracles, so you will still be in rough ballpark comparing speeds. The small corrections to comparisons between 2 will be known in time. But 2666 CAS 15 is slow and much slower than 1866 CAS 9, no getting around it.
But good news, as carhil2 linked in another thread, some of the 3000+ ram CAS15 is able to be overclocked by reducing timings to 3000 CAS 11-12, which is fast. Again why I would for reviews to come out and X99 and all ram choices to be available before buying ddr4, unless I saw some that some had leaked clocked well. Which ones overclock well via speed/reduce timings ie CAS 15 to more appropriate CAS 11 or 12 will be key.
Unless of course a couple of months after launch, much better ram comes out, in which case ebay will be littered with ddr4 ram.Edited by opt33 - 8/23/14 at 6:08am