990FX Extreme3 + 4xDDR3-1866 = Problem

Motherboard: ASRock 990FX Extreme3
CPU: AMD FX-8350 without overclocking, BOX
Memory: 4x HX318C10FBK2/8 (4Gb each, DDR3-1866, 10-11-10).
Power supply: Corsair CX750
Video: tried different cards, same result.

Problem: system is not booting if all memory is installed.
But if I install only two DIMMs (in any combination, any slots - A1+B1, A2+B2, A1+A2, etc.) its all working on 1866 timings. But all four of them can boot only if I manually select PC-1600 clocking in BIOS.

What can be wrong? How do I fix that and how do I use this setup at full capacity?

Yes, its new board with 1.90 BIOS

Its two identical kits x2 with absolutely same timings and they are working in pairs in any combination. I can make screenshots and i can take photo from BIOS page with timings.
Will update this post with pictures, but i don't think that it will change anything.

I'm not sure how I can monitor VRM temperatures without built-in sensors - I don't have equipment for this.

Memory SPD	 
DIMM #	1
     SMBus address	0x50
     Memory type	DDR3
     Module format	UDIMM
     Manufacturer (ID)	Kingston (7F980000000000000000)
     Size	4096 MBytes
     Max bandwidth	PC3-14200 (889 MHz) 
     Part number	KHX1866C10D3/4G
     Serial number	502E9A68
     Manufacturing date	Week 16/Year 16
     Number of banks	8
     Nominal Voltage	1.50 Volts
     EPP	no
     XMP	no
     AMP	no
JEDEC timings table	CL-tRCD-tRP-tRAS-tRC @ frequency
     JEDEC #1	5.0-6-5-15-21 @ 465 MHz
     JEDEC #2	6.0-7-6-18-25 @ 558 MHz
     JEDEC #3	7.0-8-7-21-30 @ 651 MHz
     JEDEC #4	8.0-9-8-24-34 @ 744 MHz
     JEDEC #5	9.0-10-10-27-38 @ 837 MHz
     JEDEC #6	10.0-11-10-29-40 @ 888 MHz
     JEDEC #7	11.0-11-10-29-40 @ 888 MHz
     JEDEC #8	13.0-11-10-29-40 @ 888 MHz

Here is CPU-z shots: timings for stable 1866 pair (they are same for any pair, so only 1 shot for this):


Here is shot for stable automatic setup for all 4 modules:


Here is all four modules, #1-#3 and #2-#4 are kit pairs (same date code). System reports about dual-channel mode, stability tests are just fine.



I'm confused by SPD data, it says about frequency 889 MHz which corresponds to 1778 (and i see this frequency in memory information tab in BIOS), but if i MANUALLY set timings as they are described in SPD data (10-11-10-29-40), then frequency goes as 931 MHz (see 1st shot for most successful attempt to get exactly 1866). This trick works only for pair (which can be made from any of those four modules). So physically they are able to work on 1866 (as they are KHX1866C10D3)

NB: I dont want to overclock it. I just want to get it working as it should be.


Edited by Tangaroa - 24 Jun 2016 at 5:49pm

that's sad news. But still. freshly mounted board will not start with 4 modules, or will crash in first seconds of work, not allowing you to change memory settings. And without special shamanic actions ("remove two modules, start system, tune settings to 1600, turn off and install remaining memory") it will not work.


Edited by Tangaroa - 26 Jun 2016 at 8:18am

Yes, I did - added 0.005V as you said, nothing changed. Few steps, by +0.005V each, same "no go" result. Don't want to burn system. And another problem: this testing will take a time, because system is just blackscreening if parameters are not good - BIOS can't use 'safe to start' default parameter set in case of emergency. So I need to install 2 modules, set new settings, install another 2 modules - nope, not starting - remove 2 modules, set new settings, test - .. DIMM sockets will be destroyed by this cruel operation. One socket is already stirring, I don't want to kill board.

Keep in mind AMD only certifies 1866 on two sticks in dual channel
I wonder what if I install 2100 memory (which is said to be supported by this board) - will it start on 2100 or again it will require some downscaling and tuning just to get system working?


If only BIOS had option for "safe guaranteed start" on lowest possible settings in case of inability to start on automatically detected settings (they can be wrong, as we know it already)...


Edited by Tangaroa - 27 Jun 2016 at 12:02pm