Louisbs Posted November 5, 2007 Share Posted November 5, 2007 Hi, I have 2 matched pairs of this ram. Unfortunately there seems to be a compatibility between the pairs. The only difference i can see is 1 set is v5.1, while the other is v5.2. While trying to run these all together, memtest fails or XP freezes on boot up. Yet when i run the sets seperately they function fine. Surely being the same brand & model they should all work together? Thinking it was my motherboard i returned it and got a loan one. So i am now probably going to get a nice fee lol Thanks Louis Link to comment Share on other sites More sharing options...
DerekT Posted November 5, 2007 Share Posted November 5, 2007 The memory controller can not keep up with the extra DRAM at the rated 6400 speed. You will need to drop the speed of the DRAM from 800Mhz to 667Mhz. If you had purchased 4 X 1024MB of PC8500 (1066Mhz) DRAM, then you would have had to drop to PC6400 (800MHz) DRAM, etc. 2 X 2048 will not issue this problem. This is a problem of all 4 B Banks being populated and is related to the on motherboard memory controller not begin able to load and access DRAM as fast with 4 Banks populated as it can with 2 Banks populated. You must slow the relationship down with 4 Banks populated. Think of it this way. If you have a small phone book, then when you go into the index to find the page where you will find the phone number you are doing so at a certain speed due to the pages of the Index. Then you have to drive through the pages to get to the number. Now if your index is twice as large and the pages twice as many, then it takes longer to access the data. Now DRAM has a Strobe and the length of the strobe is how long the rows and columns can be left open before they must be refreshed. There is not enough time for the dram to be refreshed and then accessed with 4GB at the full access speed of the DRAM. The chipsets are optimized for 2GB, not 4GB and for 2 DRAM slots, not 4 DRAM slots populated. You can overclock the FSB (and hence the Memory Controller Hub = MCH) to gain some extra bandwidth and thus access the capabilities of the DRAM since the chipset is now clocked up. Usually when you clock up the FSB and concurrently the Memory Controller Hub (MCH) you need to raise the voltages of the CPU/MCH a bit as well. Shut the system down and install two sticks. Enter the BIOS and set the DRAM to 667Mhz with 5-5-5-18 JEDEC timings. Shut the system down and install the second set of DRAM. You need to manually set this because the motherboard defaults to setting for 2 DRAM banks throughput, not four banks. Link to comment Share on other sites More sharing options...
Louisbs Posted November 5, 2007 Author Share Posted November 5, 2007 Ok thanks I will give it a go right now Link to comment Share on other sites More sharing options...
Louisbs Posted November 5, 2007 Author Share Posted November 5, 2007 Grr still no good. Put my older sticks back in. Can alter speeds now. But with newer sticks.. PC doesnt post when i alter speeds. Link to comment Share on other sites More sharing options...
DerekT Posted November 5, 2007 Share Posted November 5, 2007 It looks as though the two versions are not compatible. That's surprising really as 5.1 and 5.2 should be the same ICs, SPD, and voltage requirements. When you say that the PC does not boot with the new set and timings, do you mean that 5-5-5-18 does not boot these new sticks alone? Can you memtest (http://www.memtest.org) the new set? Link to comment Share on other sites More sharing options...
Louisbs Posted November 5, 2007 Author Share Posted November 5, 2007 My motherboard doesnt like these new sticks. I cannot alter the memory speed. System doesnt power up fully and monitor remains in standby. And yet when on default they pass memtest! :mad: Link to comment Share on other sites More sharing options...
Louisbs Posted November 5, 2007 Author Share Posted November 5, 2007 Well I am gonna sell the new sticks onto my m8. Gonna let him try them first lol Link to comment Share on other sites More sharing options...
Louisbs Posted November 5, 2007 Author Share Posted November 5, 2007 I think the oddest thing is.. they worked together from the 29th october till the 4th november :(: Link to comment Share on other sites More sharing options...
Corsair Employee RAM GUY Posted November 6, 2007 Corsair Employee Share Posted November 6, 2007 Were you ever able to test the new modules at 1.9v individually with memtest? Link to comment Share on other sites More sharing options...
Louisbs Posted November 6, 2007 Author Share Posted November 6, 2007 Yes. They went through memtest fine. I tryed 1 stick from the new pair to make a total of 3Gb.. System would post.. but memtest would show a huge drop in memory b/w and XP would load very slowly and be laggy once loaded. Put in the last stick and system wont post. Link to comment Share on other sites More sharing options...
Corsair Employee RAM GUY Posted November 6, 2007 Corsair Employee Share Posted November 6, 2007 If all the modules test OK seperately then that would suggest some issue other than the memory. It is possible that you have a combination of memory that the MOBO cannot run together. Link to comment Share on other sites More sharing options...
Louisbs Posted November 6, 2007 Author Share Posted November 6, 2007 Possibly. But these are same model. Other than different revisions. v5.1 & v5.2. Anyway I am selling the new sticks to my mate. He can make use of them. Ill just stick with 2Gb lol Link to comment Share on other sites More sharing options...
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