The tale of how a detachment of white knights of RAM with a black SSD fought

On the occasion of October 31, I offer you a fairy tale about how they fought with evil spirits, who settled not where it should be.

Fairy tale

There was a wise king in one kingdom. He once decided that there are not enough four knights in service, even though everyone could remember four gigabytes of information at once. The king decided to renew the composition of the round table, since there were eight knights in the fortress. For a long time he chose in the overseas state warriors strong, strong, reliable: not afraid of either the dragon flame or hard work, his choice fell on a team of eight good fellows about eight gigabytes each: Kingston HyperX Fury 1867Mhz.

The knights arrived at the castle, with honors sent experienced servants to rest, began to sit down at a round table, and their first difficulties began. Like a roll call in POST'e - so eight of them. How it comes to work - so the total memory capacity is not more than 48 gigabytes, and six work, but two are not visible. As they did not sit at the table, together, in the fourth, in the sixth, in those places, in these - nothing changed.

The morning roll call went fine, but it was not possible to fight: there are no two, and that’s it. They went to the magician and wizard, he showed them on a wonderful device called a monitor, a miracle book Internet, in which there were answers to all questions. To begin with, they tried to reduce the frequency to 1600/1333/1066/800 megahertz.

They decided to update the table and chairs: the new version of UEFI was supposed to immediately allow 128 gigabytes of memory to use. Did not help. Then they decided to increase the salary: they increased the voltage on the memory controller, on the modules themselves, on the control system - no result. They tried to stop paying the powerful wizard, hiring his apprentice for pennies: the effect is zero, the eight does not work, even though you crack, the sorcerer had to be taken back.

Not enough strength - ask for help and experienced warriors. They called four pensioners - they all work together perfectly, and there are eight at the roll call, and at the table, only the common frequency is 1333 or 1600. One can live, of course, only the problem must be solved somehow. Then someone said that the black dragon that was sitting in the basement could be to blame. They unhooked him from the leash and fetters, but he grabbed powerfully at the base of the tower. They twisted his wings and paws, and drove him out of the kingdom. And immediately the work was adjusted and all eight knights were able to sit down at the table and trump the full amount of memory before the sovereign. Well, then they let the dragon back, let alone live.

The moral of the tale: check not only obvious things, but also non-obvious ones.

Analysis of a literary work

Not so long ago, I decided to expand the RAM reserves to 64 gigabytes, chose a set of Kingston 's that never failed me: 8 dice with 8 GB each, 1866 MHz.

I came, put, look - in the UEFI it is displayed that all eight slots are occupied, but the total amount is only 48x1024 MB. Both in UEFI, and in system. At first, he sinned as a memory, took out two modules - still 48. I took out the other two, put in their place the removed ones - 48. Two more - 48. In general, all the connectors and all the dies were working, in any combination of 8 or 6 modules the system was visible only 48 gigabytes.


^{I beg your pardon for the quality of the illustrations, it wasn’t before the photo shoot, I took it off the intercom.}

Of course, the second logical step was checking for BIOS / UEFI updates: I downloaded the latest beta version, which directly supports up to 128 GB, installed - no effect. Then I had to google. Part of the materials indicated insufficient power, and part - the low voltage of the memory controller, which, in principle, could directly follow from an insufficiently powerful PSU. I checked by disconnecting the main consumer - the video card. All the same 48 gigabytes. He raised the voltage on the power controller, on each bracket and, a little, on the processor cores - all the same 48.

I tried to use the " MemOk!"on the motherboard, which launches self-diagnostics and auto-tuning of memory parameters. Of course, it didn’t help. Like the Asus OC Tuner, which squeezed out the processor for almost 5 GHz, but didn’t start the RAM.

I wrote in both support: both Kingston and Asus confirmed that I was moving in the right direction - they suggested the same ways to solve the problem, answered quickly and in essence,

started to sin again on my mother, decided to check what happens if I insert 4x4 + 4x8 - all the modules are visible, volume 48 (as it should to be), everything is fine. Put back 8x8 - 48.



The last device, to which could affect the operation of the RAM was OCZ's PCI-Express SSD: SandyBridge-E has a memory controller and a PCI-E controller located on the same chip, in the uncore part.



I forgot to think about it, and I changed the video card during the tests, so hands got to the SSD last. Turned off the power supply, unhooked the disk, checked everything for the hundredth time, clicked the toggle switch ... Oh miracle, everything started: 64 gigabytes appeared in the system, operating at their maximum frequency, without any tambourine and voltage increase. I decided to test the hypothesis, inserted the SSD back - everything works.


^{The test results are pleasing, almost 50 GB / s for reading and 55 for writing.}

When an SSD is inserted, it distorted the memory dies - again 48. That is, installing SSD -> RAM - does not work, RAM -> SSD - everything is fine. So, it would seem, completely unrelated things were in an extremely close correlation. I hope someone will find the description of my troubles useful, although not everyone has PCI-E disks and a mother with an X79 chipset. Well, for those who “long wanted, but did not dare” - 256 GB PCI-E drives didn’t go very far from SATA-III in speed, especially inexpensive ones (which are single-board and without internal RAID), but they cause problems in order: then there are no UEFI-compatible drivers and the system does not install normally, then they add 10 seconds to the boot time, because initialized before POST, and they load PCI-E lines. As it turned out, they also affect RAM.