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From 4GB to 8GB on Gigabyte GA-MA78G-DS3H


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Attempted to find a similar subject via search, but no luck. Point me to the right place if I've missed it, please.


I am building a new system (the one in my profile) based on the Gigabyte GA-MA78G-DS3H mobo and a Phenom X4 @ 2.6 GHz. I had originally planned on using only 4GB of RAM, and so I purchased a TWIN2X4096-8500C5D set of 2 sticks. But I've now decided to use 8GB of RAM instead. So...


1. Can I simply buy another two sticks, or do I really need to replace my current RAM with something else? I would prefer to keep this and add another two sticks, but is that feasible and advisable?


2. If I can use 4 sticks of this RAM, what settings are known to be "fast but stable" on this board and CPU? Where should I start as a "known-good" configuration when I first build the system? I usually try to do only a little light overclocking, since rock-solid stability is far more important to me than speed.





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It is advised to purchase the same version and model of sticks if you are populating all four DRAM slots. Keep in mind that the DRAM is sold as kits of two and as such are supported as a kit, not as a four DRAM slot population. Often the memory controller on the motherboard will not accept a four DRAM slot population of even identical memory modules unless the DRAM is lowered in speed so that all four DRAM slots can be accessed with stability. The general rule of thumb is to set the DRAM on bin lower. ie. 8500 to 6400, 6400 to 5300, etc.


If you look at your motherboard manual, you will see that your Phenom build will not accept four modules of 8500C5. This is due to the AMD AM2+ CPU memory controller limitations of one 1066 dimm module per channel.


Support for DDR2 1066 (Note 2)/800/667 MHz memory modules



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Thanks for the reply. I'd read that part of the manual before, but "Note 2" only says: "(Note 2) Whether 1066 MHz memory speed is supported depends on the CPU being used." Not the most helpful note, and I hadn't yet done the research on which CPUs would or would not take the 4-stick solution with aplomb.


It turns out, however, that my question is moot. I actually built the system today, and found to my surprise that my Xigmatek S1283 CPU cooler blocks two of the RAM slots. Lower-profile memory might fit below the cooling fins, but the tall heat spreaders on this RAM definitely do not. So for now, this is a 4GB box... and as soon as I can sell off these 4GB to someone, I'll buy a two-stick 8GB set.


Again, though, thanks for the response.

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As a follow-up: it turns out that I cannot find a two-stick 8GB set! Have I missed something?


What I want is 8GB of RAM that will run at least at DDR800, ideally at DDR1066. I'm using a Phenom 9950 (2.6 GHz) with a Xigmatek S1283 cooler. Since the Dominator RAM is so tall, the heatsink blocks it from using two of the four RAM slots. So I need either a two-stick solution, or a lower-profile four-stick solution.


I prefer Corsair if possible, and since I don't see a real performance advantage that justifies the price for DDR3 I went with DDR2 on this choice. I not religious about DDR2 vs. DDR3 or 800 vs. 1066... I just need it to work and be reasonably fast. I don't do heavy gaming, but I do heavy Photoshop. :-)


Can someone point me to what I should buy for this mobo/cpu/heatsink combination to get 8GB of RAM installed?



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With Phenom's, there have been issues at the 1066 level even with two sticks. It is advised to drop the bandwidth when populating four DRAM slots but keep in mind, that these modules are supported as a kit of two and not as two kits of four so it always a bit of a dice throw since there can be issues with a four DRAM slot population. This is doubly so with a DDR2/DDR3 Hybrid board.


It is advised to buy the DRAM one bin higher if you want to populate with all four dram slots. Four sticks of DDR2 at 1066Mhz. Then set the BIOS to 800Mhz with 2.1v on Vdimm and 1.45v on the MCP.


However, as I said, it is a dice throw. You might have done far better to purchase a low end Core 2 Duo and overclocked it to get the full 1066Mhz on four sticks of DRAM. As it is, you now have more of a possiblity of four DRAM slots even at 800Mhz not working. The on CPU memory controller of the Phenom is known to be wonky.


However, this is not to say that the four DRAM slot population will not work, just that the possibility of it not working is more pronounced with your hardware.


The issue is the memory controller and you may find that the memory tests out fine with Memtest but the system is unstable since it is the On CPU memory controller that is returning instability and not the DRAM.


Sorry that this information is not more comfortable.

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Yes, thank you.


I have realized that, and in my last post I rephrased the question. Let us now assume I will sell these 4GB I already have to someone, and that I now have no RAM installed.


What two-stick Corsair product should I buy to get 8GB of reasonably fast RAM into this machine? DDR2 1066 would be nice, but I suspect that for Photoshop DDR2 800 would probably be OK.



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  • 1 month later...

Sorry to go a little bit off topic, but rpaiz am I right in thinking you are running a Phenom 9950 on the GA-MA78G-DS3H, is this the 140w version only I have the same processor and board and cannot get to load windows, keeps crashing, I have Corsair Memory TWIN2X2048-8500C5D 2x1GB 240-Pin DIMM XMS2-8500 x 2 sticks. I was under the impression after looking at Gigabytes website that the board does not support the 9950 due to the higher power requirements or am I wrong, I purchased an Asus M3A78-T board as a replacement but the board is DOA so if I can get my Gigabyte board working I would be well chuffed.


Further to my last post, just checked out Gigabytes site, looks like revision 2.0 of the board supports the 9950, no such luck for my revision 1.0 board!!!!!! Damn

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