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DDR3 vs DDR2 compatibility problems

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a b V Motherboard
September 22, 2011 6:23:43 AM

Is it just me or is anyone else seen that the road to DDR3 has been a rocky-hard place?
Any DDR2 memory pretty much works in any DDR2 compatible motherboard without too much fiddling with voltages and timings. Ever since we jumped to DDR3, I constantly see problems which involve incompatibilities between motherboards,CPUs and RAM sticks.... there are dual channel kits, tripple channel kits... RAM for Intel only.., RAM for AMD only... (or at least that is what some computer shops advertise)... it is getting so confusing.

Why can't they decide to follow the JEDEC standard and go back to every single stick will work on any motherboard.

I would love to buy a set of 16GB DDR3 on special, even before I get my new PC in, but I am scared that unless I order everything together, it will not work properly and will have to send it back... (since I have not decided yet whether it is going to be an AMD or Intel system).

What do you think?
a b } Memory
a b V Motherboard
September 22, 2011 6:52:17 AM

Yes there is definitely some issues with DDR3 RAM. Technically the better suppliers do follow the industry specs but how they get to those specs varies in design. Part of the issue is that DDR3 RAM runs at a higher frequency and as such means everything must be perfect of you experience memory errors. In addition the chips that memory makers buy to make DIMMs vary a little in design and production quality.

The RAM chip density has also increased so we have more memory addresses on a given DIMM for the integrated memory controllers to read and write to. When you look at the time available vs. the time required to access the memory addresses on two or four high density RAM DIMMs, things get dicey.

It appears that RAM makers have widened the "window of operation" on DDR3 RAM in the past six months or so. There is still very little likelihood of good results with mixing RAM but if you purchase ONE matched, tested RAM kit for the specific brand of CPU then chances are extremely high that it will function properly. You see most brand name DDR3 RAM now being advertised for ALL dual-channel mobos regardless of CPU brand - but it's important to note when the RAM is not listed for both AMD and Intel CPUs. Obviously with triple channel Intel CPU/mobos you need the correct RAM and that RAM is usually NOT designed to function in dual channel systems.
a b } Memory
a c 92 V Motherboard
September 22, 2011 8:25:40 AM

Early DDR3 ram ran at 1.8v to get better latencies. Intel came out with their next chipset however and 1.8v would physically burn out the chip and board. You shouldn't go past 1.65v on these boards. Now I hear Intel is saying 1.5V max for their newest CPUs, requiring even better ram. AMDs pins are bigger, so they don't have this issue. If Intel gave us boards that could handle voltages higher then spec we wouldn't this issue either. Perhaps DDR4 will fix this for us.

I'd like to point out that I had no issues moving to DDR3. I picked up some name brand (corsair? G.Skill?) DDR3-1600 that had a 1.5v profile. I didn't have any issues getting it to work in my P55 board.
a b V Motherboard
September 22, 2011 12:57:18 PM

Thank you for your feedback guys. It seems I will have to wait for Bulldozer (not for too long I hope) to make my mind whether my next PC will be an AMD or Intel and then decide on the RAM depending on the CPU and mobo.

:) 
!