Well, I care, because I know, that I will be clock-limited harshly on my X58 platform, so I asked these crazy overclockers and get some extensive inside knowledge and finally bought a triple channel ram kit that do 6-6-6 timings at 833MHz 1T with 1.72V:
On more serious note, they can do 7-7-7-20 1T @ 903MHz:
The "trick" is to know the memory chips that are used there. There is a big list there: http://ramlist.i4memory.com/ddr3/
"This kit is one of the most prominent kits with Elpida Hyper ICs. No other IC can do these specs anyway."
And the "gold" chips are Elpida Hypers only. Either the old Elpida MNH-E Hyper, of the new Elpida MGH-E Hyper chips, witch are made after Elpida screwed up and bunch of the rams end up dead: http://www.vrworld.com/2009/07/22/corsair-re-launches-elpida-hyper-based-dominator-gt/
"MNH-E Hyper had a little problem of dying randomly. At this point, any MNH-E Hyper kit that is still alive isn't affected by the problem."
In short, best bins of Hypers have 7-8-7 ratings at 2000MHz 1.65V guaranted. An example of such kit is there:
Corsair Dominator GT CMG6GX3M3A2000C7 (Elpida MGH-E Hypers)
They can do real 1330MHz (2660MHz) with 7-8-7-20 1T settings:
And since I going to use WinXP, then I did not care about the fact, that 3x2G is "only" 6G of ram. XP cannot address more that 4G of ram and when I cut down the 512MB of graphic card memory and some buffers, I will be glad to get 3.2G of ram free But that is plenty for WinXP.
As the real-world difference goes, it is really small. I did some tests and between 9-9-9 and 6-6-6 timings are the differences in Cinebench 11.5 almost none:
8.13 points 9-9-9-24 2T: http://hwbot.org/submission/2934676_ (G.Skill Dual channel)
8.14 points 6-6-6-18 1T http://hwbot.org/submission/2935830_ (Corsair Triple channel)
Just installing GFX cards drivers give more boost:
8.17 points 6-6-6-18- 1T http://hwbot.org/submission/2936196_ ;D
(yea, previous scores are on VGA M$ driver, witch is, of course, nowhere near optimal or fast ... I was just playing with the HW a bit...)
Price-wise it is absolutely irellevant I say. And I specifically bought very good ram (8-8-8-20 1T 2000MHz is not best Hypers bin) because I fear, that 6 cores and 12 threads need every bit of memory bandwitch I could get. Turns out that even in well paralelized app, the 12MB of L3 cache helps enought to make memory timings almost irelevant.
I won't believe it before, but the tests show it all too clearly. I can only hope that I can find a test, where these rams shine
And hopefully these informations will be relevant and helpfull to someone. It took me weeks to collect that info. And I must admit that I'm AND guy and I hated 2T rams (for the slow-down they cause on AXP/Opteron processors) and considered them worthless garbage. So I was specifically determined to prove this my point of view... and I failed. I have yet to find out an app, that show dramatic speed-up for 1T and tight timings.
IMHO there is none, but I will gladly be proven wrong ;D