I just setup a Gigabyte MA790FX-DS5 with a PHENOM 9500 and 2 sticks of Crucial DDR2, 1GB, 800 memory. I specifically chose this memory because it was on Gigabytes list of approved memory for Dual Channel. However, after trying every slot configuraton I can think of, the PC will only boot in "unganged" 64 bit mode. Any ideas on what needs to be changed? Timings?
We should note the new unganged mode, when the integrated controller acts as two independent 64-bit controllers, which can service memory calls from different processor cores. According to our test results, this is actually a single-channel mode for single-threaded access to a single data block (and it demonstrates appropriate values of real memory bandwidth). However, it becomes much more efficient for multi-threaded access to several data blocks. It becomes even more efficient than the ganged mode of the memory controller, which can be considered a classic modification of the 128-bit dual-channel memory controller. Efficiency of the unganged mode is especially noticeable with fast memory (e.g. DDR2-1066), when it can reach memory bandwidth values of about 85% of theoretical maximum. We have never seen such a big step to revealing the full potential of DDR2-800 and DDR2-1066 memory. And we can now say that the memory controller integrated into AMD processors has finally managed to demonstrate its indisputable advantage over the traditional bus architecture of Intel platforms.
According to the end of the article unganged is alot more efficenct then ganged...... This will result in single channel mode but bandwidth will actually be increased. But yea as g-paw says switching to ganged should allow for dual channeling mode. I don't own an AMD platform so I'm not sure how u switch the modes, prolly the bios.
The manual that comes with the motherboard says that slots 1 & 3 should be used for Dual Channel. However, if you go to their web site and look at the updated manual online, it says to use slots 1 & 2 for 2 sticks of memory. This resolved the problem and I am now in ganged mode. I will take your advice and run benches to see which is really faster.
I've searched everywhere and tried every suggestion and I am still unable to get my dual channel to work (or to get any RAM recognized in slots 2 and 4). I have a Gigabyte GA-M59SLI-S5 and matched Kingston KVR800D2N5/1G. I can get any and all combinations to work perfectly in DIMM slots 1 and 3, but only single channel. Memory is recognized in slot 2 but not used, i.e. POST info shows slot 2 is filled but memory is not credited. If I put ANYTHING in slot 4, the system won't boot. Also, the system won't boot if memory is only in slot 2, or in slots 2 and 4. Any ideas? Please don't suggest getting latest BIOS, make SURE RAM is matched, make sure RAM is compatible with MOBO because I've checked all.