Can't OC with 4 sticks - works fine with 2

[Notlag]

Just want to get other folks input on this:

With 2x 1GB OCZ Reaper DDR2-800 memory I can get 1000MHz no prob (400 x 2.5) with 5-5-5-15 timings using 2.2v (which the memory is still warranted for). When I add two more sticks of the same memory, to bring it up to 4GB, I have to drop back down to 800MHz, and even then can only manage 5-5-5-15 (when the memory is spec'd 4-4-4).

I still have to try the two new sticks as a single pair to see if it will hit 1000MHz on its own (it should - it's the same exact memory, and 1000MHz w/ 5-5-5-15 timings is not an extreme OC for that memory) and will post the results when I do, but does anyone have any suggestions or ideas in the meantime?

I've heard others complain about difficulty overclocking memory w/ both banks filled. Does anybody know the real primary cause of the problem? OC'd memory becoming ever so slightly eratic and interfering w/ eachother when there's more than one DIMM in a given bank? Could my PSU be an issue (the added memory causing more voltage drop on that rail? I'm probably pushing my 550W PSU already w/ overclocking my Q6600 - my wall outlet power consumption is in the 360W neighborhood).

Intel Q6600 G0 @ 3.6GHz (400 x9) 1.4125v
Thermalright U120X w/ 140CFM Delta
Gigabyte GA-P35-DS3P (stock northbridge voltage)
2x 1GB OCZ Reaper DDR2-800 @ 1000MHz (400 x2.5) 2.2v
Nvidia GeForce 8800GTS 320MB

[meionm]

Up northbridge voltage, cool it better, northbridge manages memory.

[Notlag]

Up northbridge voltage, cool it better, northbridge manages memory.

I'm pretty familiar w/ CPU cooling, but not very familiar w/ northbridge cooling. Right now I have the stock cooler on it for my mainboard (it's a heatpipe based cooler with a fair amount of fin area but not connected to the other mainboard heatsinks), but I've added a 40mm fan for additional airflow (admittedly, a 40mm won't add much).

Without replacing the stock northbridge heatsink, how far can I reasonably push the P35 northbridge voltage w/o affecting component life? Or will upping it require additional cooling (in which case I'm comfortable checking out available options and selecting something best-of-class for air)?

[Notlag]

Turns out the two new sticks just don't overclock well. I pulled the original pair from the system and replaced them with the new sticks, and the new sticks won't clock to anything over 800MHz (well, to be fair, they won't clock to 960MHz - I don't have a multiplier in between and don't want to lower my FSB to raise my memory clock). Interestingly enough, if I pull up the info on them in CPU-Z, they come up w/ a different part number, even though they're labeled the same on the DIMM's and on the packaging. I will see what OCZ has to say about this.

Oh, and raising the NB voltage didn't end up helping :( I didn't go over +0.2v, but even that amount made no difference (ie - didn't run for longer before crashing or anything - same exact behavior).

EDIT: The memory won't even run the 800MHz 4-4-4-15 advertised timings w/ 2.2v (which is 0.1v over the spec voltage, but still within the memory's warranty). I'm going to either RMA it w/ the manufacturer for a replacement, or just return it outright and order some DDR2-1066 memory (*cough cough* mostly ordered the heatpipe memory because it looked cool in the system - disappointing that only the first pair performed well).

Also, the part number the new pair comes up as in CPU-Z is "OCZ2RPR8001G", versus the part number on the box, on the label, and on the original memory in CPU-Z, which is "OCZ2RPR8002GK". Makes it appear the manufacturer is subbing in unmatched or sub-standard parts to meet production demand (though there's no conclusive evidence to that - just doesn't look good when it doesn't work and comes up w/ a different part number).

[Reefa_Madness]

Just an FYI, but I believe that the difference in your parts number is only due to the fact that one set (OCZ2RPR8002GK) was labeled as a "2 gig kit", while the other set was made up of two individual 1 gig sticks (OCZ2RPR8001G). It is the same stuff, just the "packaging" is different.

Follow the link for a similar discussion on another forum:

http://www.ocztechnologyforum.com/forum/showpost.php?p=229624&postcount=2