For a number of reasons, I'm running a Q6600 (at 3.6GHz) with RAM in single channel (one 2gig stick). Will there be a noticeable performance hit because of the decreased memory bandwidth? I read an article on Tom's Hardware that said the difference between single and dual channel is negligible (~4% max). Other sources, most of which are far less credible, say an up to 10% performance hit. Others say the number can be even higher. I'm just curious what some of you guys know/think regarding this issue.
50% in theoretical bandwidth, and about....less than 5% of performance hit. As Dr. ( ) said above, Core 2 does not benefit much from increased memory bandwidth. The FSB itself is a limiting factor (10.6Gb/s FSB vs. 12.8Gb/s in DC)
Great. I knew the "50% hit" was hogwash, but I didn't know exactly how true it could be. I can live with a 5% loss. The issue was, my system just would not go beyond 2.8 GHz with 4 gig of RAM installed. After messing with the voltage, and every possible thing you could think of, taking out one stick was the only solution. Given that it was a 2x2 gig set, I'm only running one 2 gig stick. Hence the questions regarding single vs. dual channel mode. Of course, I could just return the 2x2 gig set and get a 2x1 gig set, but I really don't know if I feel like it, considering the system is running just fine at this point. I've done exactly 15 hours of small FFTs as of this moment (planning to let that go to 18 hours). Assuming it passes small, I'm going to run 8 hours of large, and 8 hours of blend. If it passes both of them, and gives me a decent 3dMark, I'm just going to ebay the other stick and call it a day.
You wont notice a difference at all unless you do memory benches and those will very small differences anyways. The real performance loss is the actual 2 gigs of ram itself. Thats if you are using apps/games that benefit from having the extra 2 gigs of ram.
Keep in the mind that was test was done a c2d e6850 system. The performance hit for the quad may be a tad more since it has more cores and a slower fsb(at default). But it also has a little more cache.
I dont know how well AMD systems will peform in dual vs single channel. They do take hits with slower memory but i dont know about the difference in single vs dual
I was looking at the wrong specs for my RAM....thought it needed 1.8-1.9, when in actuality it needed 2.0-2.1v. I have both sticks back in the machine, running at 2.112v, dual channel, no problems. The single vs. dual channel thing is good to know, though.