I bought 8GB of this RAM which is DDR2 1066 with timings of 5-5-5-15 according to the specs listed.

My BIOS picked it up as 800 /w 5-5-5-18, so I had to mess with settings to get it at 1066. This gave me 5-7-7-24 timings. I changed it to 5-5-5-15 but then memtest86+ 4.20 started finding errors (in test #7 if it matters). Changing the timings to 5-5-5-18 @ 1066 seems fine.

Now to be honest I have only a vague idea of what this all means (I'm not looking for an explanation or anything though). What I want to know is if I'm missing something that I should have known, or if I should return the RAM as defective. Or does it really make a difference to have that last number 3ms longer than it should be? Or is it common to advertise the best numbers even if you can't have them all at once?

I know this isn't a tech support forum, but this is vaguely game dev related... indirectly... I mean, this is for my dev & gaming box... I want to be able to run a couple VMs and compile while still running around shooting guys in the face.

Thanks for any wisdom or info!

I probably wouldn't sweat it unless you're an uber overclocking benchmarker shooting to increase your 3dmark score by 5 points.

You could try to increase the voltage a touch to achieve a slightly faster timing if it's important, but I'd wager you'd never notice the difference. Maybe you can replace it and get one that's slightly faster, but it's not really guaranteed.

And it's not "3ms" longer, (the number is clock cycles, not ms), so really it's only slightly less than 3ns slower.

As far as their advertising, when you spin wafers of silicon the speeds it can operate at follow a Gaussian distribution, so each stick of ram can operate a little faster or slower than the next one. They just have to pick a timing to advertise that maybe 95-98% of their hardware can hit, and just write off the rest as defective. RAM's a cutthroat business with razor thin margins so I wouldn't be surprised if some slower parts slip out or they over-advertise by a hair. It will depend on lots of other factors too, any noise on your mainboard, the temperature of your case, etc, etc.

Basically I wouldn't worry about it.

The number one "but it should work" in custom-built PCs* is memory+motherboard. It's not just a matter of number of cycles -- the precise shape of the waveforms, and the relative timing of different signals, will affect whether things work all, most, or none of the time. It's possible that different sticks of the same model would work at those timings with your motherboard, and it's possible that a different motherboard of the same model would work with those sticks, but for three RAS cycles (that's the last number) I wouldn't bother. If you really feel like it, and your BIOS offers the options, you could try playing with voltage and clock skew -- neither one's gonna destroy your RAM as long as you don't go wild with the voltage.

Personally, I'd rather have a system I can count on not to crash than a system running 5% faster. I routinely underclock my CPU and RAM.

[size="1"]* Coming in at a close second, the "800 watt" PSU you got off eBay from some guy in North Korea.

Cool, thanks guys! I just wanted to make sure I didn't have a broken product. I'm not in to overclocking (much) so now I'll be content.