Looking for "intel" about G.SKILL "Black-Pi" modules

[BonzaiDuck]

Early in January, I think, I posted here about these $50+ kits from G.SKILL in the "Black-Pi" model-line. I think they come rated as DDR2-800, DDR2-900 and DDR2-1000/1066.

I bought the 900's, but I'm guessing I'd get the same performance from either the 800's or the 1000's.

My hunch was right about these 900's, though. The warranty voltage range is 2.0 to 2.1V, and you can punch down the rated (at 900 Mhz) latencies of 4,4,4,12 to 4,3,4,9 and run them at 1.975V and between 820 and 850 Mhz. I'm still tweakin' 'em and stress-testing.

Has anyone had any luck getting the tCL down to 3 on G.SKILLs running at 800 or above?

 

[n7]

Highly unlikely, if not impossible, that you'll get tCL to 3 at DDR2-800+ on any 2 GB DIMM...only Micron has ever really done CAS 3 well, & that's been at ridiculous voltages (not in 2 GB form though).

The fact that you are running 4-3-4 tells me you are likely running nForce, as that wouldn't like happen with an Intel chipset, correct?

We are talking tCL-tRCD-tRP-TRAS, right?

Assuming we are talking tCL-tRCD-tRP-TRAS (in that order), usually you can do 4-4-3, but 4-3-4 is odd, never really seen that possible with 2 GB DIMMs at higher speeds.

I'm talking about 2x2 GB kits below:

The Pi Black DDR2-800 & 900 use Qimonda ICs (yours)

The Pi Black DDR2-1000 kit is ProMOS, same (though lower binned) stuff as in the DDR2-1200 kit, which is just amazing stuff; most of the 1200 kits can do DDR2-1300 5-5-5 at very low voltage...beautiful stuff.

Majority of the other G.Skill kits use PSC, though the DDR2-1100 Pi kit (not Black) uses ProMOS as well.

I've seen no results from people using the Pi Black DDR2-1000 kit, so i can't say how it does, but DDR2-1000 4-5-4 is amazing - no other IC for 2 GB DIMMs can do that (only ProMOS).

The 1100 kit doesn't seem to do so well; it seems to be the stuff that can't make the 1200 bin...so it's not too hot.

The Pi Black 800/900 kits are good for being nice cheap CAS 4 up to 900-950 kits.
But they do poorly for CAS 5 (not much over 1000 usually), & on any Intel chipset, you want speed, not timings, for the best performance, so i really don't find the Pi Blacks very exciting.
I suppose for the selected few running nForce & want synced 1:1, those Pi Black kits make sense.

For Intel though, i'd recommend something capable of doing DDR2-1000 to 1100 CAS 5, & there are lots of cheap PSC kits that can do that.

 

[BonzaiDuck]

Originally posted by: n7
Highly unlikely, if not impossible, that you'll get tCL to 3 at DDR2-800+ on any 2 GB DIMM...only Micron has ever really done CAS 3 well, & that's been at ridiculous voltages (not in 2 GB form though).
. . . . .
. . . . .
I suppose for the selected few running nForce & want synced 1:1, those Pi Black kits make sense.

For Intel though, i'd recommend something capable of doing DDR2-1000 to 1100 CAS 5, & there are lots of cheap PSC kits that can do that.

Thanks for your input here, N7.

I can see your point, and -- yes -- prove it -- about speed vs timings in the DDR2 and post-DDR2 era.

You're right about my chipset: nVidia 780i. Originally, a very modest [self-disciplined] over-clock of an E8600 to only 4.0Ghz. And that was with the DDR2-1000's you mentioned (2x2GB). I couldn't help myself, and picked up this $50+ kit of 2x2GB "Black-Pi" 900's. It was maybe three weeks before I got around to swapping them into the system.

Once that was done, I started looking to boost the over-clock to just 4.20 Ghz, but found myself shooting for 4.25, planning to use those settings for 4.20. After LinPack testing, I decided to hold the 4.25 Ghz speed. Marvelous -- in my opinion -- for my conservative approach and caution.

Before "going there," I loosened the 4,3,4,9 timings back to the stock 4,4,4,12. The RAM voltage is still set to the 2.0V bottom of the spec-range. Now, I've set the timings back to 4,3,4,9 again. No voltage increase @ DDR=850. And so far, no PRIME95 "blend" failure.

As I understand it, dropping tRCD (and/or tCL) means you can drop tRAS to just +2 above the sum of the former two timings. Supposedly tRCD has a "moderate" effect on bandwidth with some small risk to stability if you can knock it down. And by itself, tRAS wouldn't have much of an impact on bandwidth -- except for this: You can knock down tRC to equal or slightly greater than tRP+tRAS, with an enormous (relatively speaking) impact on bandwidth.

So now, with CPU : RAM of 1:1, I'm getting close to an Everest benchmark "read" bandwidth of 12GB/sec.

It'll be interesting to see what G.SKILL does with DDR3, and I have yet to take a look at what they offer to compare with other brands and manufactures. I really became impressed with G.SKILL after I and a slew of other folks had their short-lived love affair with Crucial [Ballistix or Tracers].