Haines Brown wrote:
In the past I've had no problem picking RAM according to motherboard
specifications and had no trouble, but this time the more I investigate,
the less comfortable I become.

I have a GA-H97-D3H motherboard (not overclocked) and need 16 Gb (4x4)
DDR3 SDRAM, preferably by G. Skill. The Gigabyte website recommends RAM
that I can't find, and a web search did not help. Your advice
appreciated.

Haines Brown

http://www.gskill.com/en/configurator

GA-H97-D3H (Table seems to stop at DDR3-1600...)
http://www.gskill.com/en/configurato...147&model=2200

Example:

[RipjawsX] F3-12800CL9Q-16GBXL
DDR3-1600 (PC3-12800)
16GB (4GBx4)
CL9-9-9-24
1.50 Volt

$170 and still in stock
http://www.newegg.com/Product/Produc...82E16820231429

The manual for the motherboard says:

http://download.gigabyte.us/FileList...h97)-d3h_e.pdf

"Support for DDR3 1600/1333 MHz memory modules"

If I go to ark.intel.com and select a 4790K processor, it lists

Max Memory Size (dependent on memory type) 32 GB
Memory Types DDR3-1333/1600

So the motherboard appears to stick with the Intel recommendation,
rather than going crazy with overclocks.

The XMP profile scheme can cover more than one RAM configuration,
but typically what seems to happen, is a two-DIMM setup the XMP
will work, whereas if you use four DIMMs, you have to set it up
yourself. I think I've seen some mention of some set of sticks
having a four DIMM XMP entry in the SPD table, but it probably
isn't all that common. In this case, since the memory stays
at stock voltage anyway (1.5V, rather than 1.65V needed for
the faster stuff), it's probably not that big a deal whether
XMP works or not. I have RAM here, that the XMP sets it to
1.65V automatically, the Intel recommended "max" for Vdimm.

*******

Your motherboard choice is a $93 motherboard.

http://www.newegg.com/Product/Produc...82E16813128712

The dimensions 12.0" x 8.4" help indicate the class. The
more expensive a board, the wider it is. When they get
down to 12.0" x 7" or so, they're really cheap (probably
two DIMM slots). So if you didn't have pricing information,
the dimensions can give a hint where it is positioned in
terms of market tier. So your board is a "no fooling around",
"let's get this computer running" kind of board. When the
board gets too narrow, there is no mechanical support on
the right hand edge (as the mounting holes are missing
on that edge).

Your board has an extensive CPU support chart, and I don't
see any immediate danger signs there.

http://www.gigabyte.com/support-down....aspx?pid=4962

Notice the processor at the top of the chart requires BIOS
version B4.

The board appears to have four phase power, but since Haswell is
a two-stage powering scheme, not as much current flows in the first
stage as on other motherboards. The onboard regulator does 12V to 2.4V
regulation (and I've seen two different figures now for that voltage
and don't have a good reference on the subject). The Haswell has
FIVR, a thin film switching regulator system inside the processor,
that makes the ~1.0V for the CPU die. The advantage of FIVR,
is the power can be more steady in there (shorter distance from
regulator to distribution plane). The disadvantage is any heat
created by that regulator, adds to the thermal load of the processor
(part of the TDP).

A recent announcement suggests Intel is phasing out FIVR on the
next generation processor. And there was no indication of
why the change of heart. The scheme was extensively tested,
so it's not that it doesn't work. Maybe as processor power
levels drop in the future, FIVR is overkill, and an external
regulator is again "good enough" for Intel :-)

Paul