Haswell IMC

[Concillian]

FYI, the Haswell memory controller seems to be signficantly better than the IB one. At least in my own experience.

I have been playing with the Samsung memory that was such a good value a year ago or so. This stuff: http://www.newegg.com/Product/Produc...82E16820147096

It always seemed like my sticks were a little under par. I couldn't get them stable at 1866 without running CAS10. and anything above 1866 was a definite no go without very high latencies. That was on my wife's IB machine. They were still a very good value, so I was still happy to run them at 1866 CAS10.

Fast forward to this week when I got my Haswell setup on the test bench. Same sticks are doing 2133 at 10-12-12 (1T) with Haswell. They wouldn't even run that speed at CAS 12 on my wife's IB. They passed my stress tests at those speeds (IBT, AIDA64), but I like margin and will run them at 2000 with the same timings and voltage.

Just giving people a heads up on this. Whatever your sticks were able to run on IB or SB, they may be able to run significantly higher (or lower latency, or both) on Haswell. While this may not translate to a ton of additional real-world overall performance, may as well take what you can get, right?

 

[VirtualLarry]

And then there is this - Haswell supposedly incompatible with 1.5V memory. (Laptop)

http://rog.asus.com/forum/showthread.php?33744-Upgraders-1.35V-memory-is-required

 

[zir_blazer]

Desktop Haswell supports officially ONLY 1.5V DDR-3 Memory Modules.

I don't know how everyone here seems scare about RAM Voltage when running it at out-of-spec values is exactly the same that overclocking/overvolting the Processor or Video Card.

 

[BFG10K]

Desktop Haswell supports officially ONLY 1.5V DDR-3 Memory Modules.

This isn't true; desktop parts fully support DDR3/DDR3L ('L' is the low voltage variant). Here's a screenshot from Intel's Haswell Datasheet PDF (red arrow added by me):

Also for the record I've been running 1.35V/1600 memory on my i5 2500K without issue for many months, and the BIOS fully recognizes the lower voltage.

 

[zir_blazer]

This isn't true; desktop parts fully support DDR3/DDR3L ('L' is the low voltage variant). Here's a screenshot from Intel's Haswell Datasheet PDF (red arrow added by me):

Also for the record I've been running 1.35V/1600 memory on my i5 2500K without issue for many months, and the BIOS fully recognizes the lower voltage.

Check the Link. From a official Intel PDF, they support DDR3 or DDR3L, but at 1.5V.

Yes, you can use 1.35 and 1.65V modules and it will work properly regardless that. But 1.5V is the default specifications. Or if you're picky and don't want to run Haswell IMC out-of-spec, ignore your memory modules default specs and run them at a JEDEC standard setting.

 

[mavere]

Check the Link. From a official Intel PDF, they support DDR3 or DDR3L, but at 1.5V.

DDR3L, by definition, runs at 1.35V.

Edit: it seems like the link you provided doesn't concern Haswell?

Edit 2: Ha! Intel basically tried very hard to word around "we can't do DDR3L".

 

[zir_blazer]

DDR3L, by definition, runs at 1.35V.

Edit: it seems like the link you provided doesn't concern Haswell?

Oh, you're right. PDF refers to Ivy Bridge, not Haswell. Still, if DDR3L by definition runs at 1.35V, you should ask Intel what they were smoking when they said that they support it, but at 1.5V.

The equivalent of that PDF for Haswell is this one, and it says...

DDR3/DDR3L I/O Voltage of 1.5 V for Desktop

I suppose they're talking something else, not VDIMM. Else, they're not making sense. In Ivy Bridge PDF it says...

System Memory Interface I/O Voltage of 1.5 V
DDR3 and DDR3L DIMMs/DRAMs running at 1.5 V
No support for DDR3L DIMMs/DRAMS running at 1.35

So 1.5V is for I/O, but they're not saying if they support DDR3L... but at 1.5V.