RAM timings, XMP and MemTest: please help clear up my confusion

[ZenMaster]

Hello G.Skill community,

my today?s questions are about RAM timings, XMP and MemTest86+.

Hardware specs:

- Intel i7 3770K not yet overclocked
- Prolimatech Megahalems Rev.C
- Gigabyte Z77X-UD3H F18 BIOS (the newest non-beta BIOS)
- G.Skill RipjawsZ 4x4 GB PC12800 (http://www.gskill.com/products.php?index=427), compatible to the mainboard acc to manufacturer
- MSI GTX680 TwinFrozr III 2 GB
- Seasonic x-560 PSU
- 1 SSD, 3 HDDs
- Win7 64bit

For you to understand what I am currently on, I will try to give a short summary:

In the past 2 or 3 months, I had 2 bluescreens on my PC (the most recent one error code 0x24), and now I want to figure out what?s going on.
After reading a lot through forums etc, I figured, it may be a good idea to do a Memtest (with MemTest86+) while I am at work, so it can complete a few cycles.
So I went to the BIOS, and noticed, my RAM timings were set to 11-11-11-28 (I guess), but my memory should have 9-9-9-24 (at least that?s what G-Skill shows on the web page). After activating XMP, it showed the correct timings of 9-9-9-24.

First questions:

1) Should my BIOS detect 9-9-9-24 timings normally on AUTO settings, or is it the usual way, that it detects the "higher" timings?
2) Is it recommended to activate XMP, or should I enter the timings manually (out of experience)?
3) Will the RAM Voltage be altered on XMP, too, or will it still work at 1.5 V? Does XMP need higher Volatges?
4) Are the timings from the BIOS used for Windows? Meaning: if BIOS detects 11-11-11-28, can Windows still use the 9-9-9-24 settings, or are the BIOS settings taken for Windows directly without change?

Well, MemTest86+ is now running, and it showed the timings of 9-9-9-24, just as I expected. But the RAM speed is given with 800 MHz.

5) Is this due to the RAM being DDR ram, so it is perfectly normal it only shows 800 MHz in MemTest?

It would be great if you could answer those 5 questions, as I am a little confused right now.

Thank you,

ZM

[Tradesman]

1) AUTO settings are the mobo default settings
2) XMP is best for most people unless you are familiar with setting the timings manually, it will also set the advanced timings manually ...and...if needed set voltages,OC on the CPU etc (if needed, for 1600 no changes should be needed if the default is 1600, some mobos default to 1333)
3) Sort of answered in #2, this set doesn't need higher DRAM voltages, some do, so if needed (say you had a 2133 set XMP would make the adjustments.
4) Windows should take and use what the BIOS is set to - if using CPU-Z to look at things don't get confused about timings, Max Bandwidth, etc - see my info thread here:

http://www.gskill.us/forum/showthread.php?t=10565

5) Correct, DDR (DOUBLE Data Rate) will show up in most utilitiy programs as the true freq - here 1600, being DDR you take freq x 2 = effective freq

Hope this helps, if more info needed, give a shout

[ZenMaster]

Thank you very much for the answers to my questions (I know why I have bought G-Skill RAM again).

Right now I have just one little thing about question 1:

You are right, AUTO is the mainboards default setting; what confuses me is:
I expected the BIOS on AUTO to show 9-9-9-24 timings, but it showed 11-11-11-28 instead on AUTO.
To get 9-9-9-24, I had to activate XMP (I am not planning on overclocking RAM beyond 1600 MHz).
So I?d like to know if something went wrong during the detection of timings in BIOS on AUTO settings, or will I only see 9-9-9-24 when enabling XMP?

[Tradesman]

Well then that's there default for 1600, (a little loose for my taste) and one of the reasons they don't mess that much with advanced timings - as they test DRAM at the mobos default - see this thread also:

http://www.gskill.us/forum/showthread.php?t=10566

this explains why they often show very fast DRAM on their QVL but then people buy it and it doesn't work, they test at the default not the rated freq

[ZenMaster]

Sry to bother you again, but I found something strange:

When setting the BIOS to AUTO detection, this comes up (please note I took the pic while trying to set the XMP settings manually, so please disregard the values in the blue boxes to the right for now, as I dont have any other pics right now):


The 11-11-11-28 applies to both channels.

However, while the BIOS is set to AUTO detect, I can see different values in the M.I.T:


Here, the expected 9-9-9-24 are shown.

Do you have an idea if this relates to your previous answer? I mean, it looks like the modules are reporting 9-9-9-24, but the BIOS says: screw that, I want you to run on 11-11-11-28. I have no idea how this fits together.

[Tradesman]

Looks like the default is 11's and under auto detect it's reading the 9's from the SPD of the sticks