I have 2x2Gb Kingston Xyper X 1600 (KHX1600C9D3/2G) in my motherboard,
when i put anather 2x2Gb, my PC is dead.
What can i do? PLZ HELP!
I had a similar problem. Seems the GA-P55-UD6 chokes with more than two memory modules. All was fine with 2x2Gb sticks of Corsair TR3X6G1600C8G running at rated voltage, speed, and timings: 1.65v, 1600 MHz, 8-8-8-24, but when I added 2 more sticks (four total) all hell broke loose. After dumbing down the RAM settings in the BIOS, I have a mostly stable system. Here's what I did:
1) Enter the BIOS and select MB intelligent Tweaker(M.I.T), press Enter.
2) Select Advanced Memory Setting, press Enter
3) Make the following settings:
Advanced Memory Profile (X.M.P.) [Profile1]
System Memory Multiplier (SPD) [10.0] (this reduces the memory frequency from 1600 to 1333 MHz)
Performance Enhance [Standard]
DRAM Timing Selectable (SPD) [Quick]
4) Save settings and exit
Don't use the Fail-Safe default settings unless your RAM only requires 1.5v. Updating the BIOS from F3 to F6 made no difference. Gigabyte has since released BIOS update F7 (2010/01/28) for the GA-P55-UD6 which is supposed to add "Enhanced memory compatibility." I've not tried it.
Incidentally, this is my first, and last, Gigabyte motherboard. Internet forums are littered with similar woes. I don't feel that the GA-P55-UD6 should have been unleashed on the general public without first addressing the memory issue. I also think it's misleading to advertise six memory slots because of the weird mix of both single and double-sided RAM modules required to make use all six slots.
I too have a very similair problem with this mobo (F9 bios version) and Kingston Hyper X C7 1333 8gb kit (4x 2gb) memory
I have BSODs and memory errors when running 4x2gb at XMP settings (7-7-7-20), but when running with 2 modules there are no issues at all. Reducing the memory timings manually to 9-9-9-24 @1.5 (1333mhz) solved the problem but affects performance ofcourse. (No overclocking)
Side note Gigabyte Easy Tune 6 shows significantly different timings in the timings table for my 4 modules, one of the modules even has a different manufacturer (GENNUM). Should I return these modules? I presume this is not normal right?
Sorry for picking up this old thread again but I found the solution!
The default BCLK of the Gigabyte GA-P55-UD6 is 136mhz instead of the conventional 133mhz.
Therefore, after multiplication with the memory clock multiplier, the memory is clocked at a slightly higher speed than what the timings are rated for. (My 1333 mhz memory is clocked at apprx. 1360 with the 136 BCLK instead of 1330mhz, its 7-7-7-20 timings are rated at 1333mhz)
At this slightly higher speed your memory controller may not be able to handle the strain of maintiaining the rated memory timings for 4 modules (this was not an issue with 2 modules). Fixing the BCLK to 133 fixes the issue and allows your memory to run at its true speed and rated timings (at least it did for me ). You lose the 2.2% BCLK advantage though.
Alternatively you can always slighltly increase your timings.