AnandTech reports here (see link) that they pushed low-end 1.8v DDR2-533MHz memory to 800MHz with 4-3-3-8 timings at 2.1v indicating that high-end, low-latency memory is NOT a necessity for overclocking (even if high-end RAM does provide the very best results).
http://www.anandtech.com/mb/showdo [...] =2797&p=17
Regardless, it would seem from what I’ve read that having memory that will initially post at stock 1.8v is important. For instance, many people report first-day boot failures with 2.1v OCZ modules – having to resort to low-end 1.8v RAM so they can get into BIOS and increase their vdimm setting before the high-end RAM will work. Well, I supposed I can borrow a stick of cheap DDR2 memory from somewhere for a day if I have to.
Moreover….as you know, the Allendale/Conroe CPU multipliers look like this:
E6300 = FSB x 7
E6400 = FSB x 8
E6600 = FSB x 9
E6700 = FSB x 10
The Asus P5B Deluxe (which I’m most interested in) has the ability to override the locked CPU multiplier down but not up. (According to AnandTech, Asus says that some chips at random can be unlocked both down AND up but I haven’t seen anyone confirm that). Anyway, numerous articles I’ve read claim that the Allendale/Conroe chips with higher CPU multipliers overclock better since the FSB doesn’t have to be pushed as far before the CPU maxes out (lower FSB puts less stress on the NorthBridge).
I’d hate like hell to spend extra $$ for an E6400, then have to clock it DOWN to a 7x multiplier and then also find WORSE overclocking results than if I’d just bought an E6300 in the first place!
BOTTOM LINE: In your opinion....
- is DDR2-533, DDR2-667, or DDR2-800 memory the best overclocking value??
- is the best overclocking choice an E6300 or an E6400 ??
- which Allendale Stepping and Revision seems most ideal ??
I've been looking at this some more and the Xbitlabs article, though fairly comprehensive, has a big flaw; they didn't show the effects of overclocking any of the RAM. Thus, their conclusion should have read, "even with bad timings (memory run at) DDR2-800 works faster than (memory run at) DDR2-600 with the best timings.”
Duh. With Core 2 Duo, RAM performance is more clock-dependant than it is latency-dependant. Essentially, they were saying that a 300MHz FSB with tight RAM timing doesn't perform as well as a 400MHz FSB with loose RAM timing. That doesn't contradict the AnandTech article at all - the point just wasn't clearly made by Xbitlabs. AnandTech took value RAM and overclocked all of it to DDR2-800 with the best timings/voltages and found it surprisingly close in performance against high-end RAM with tighter timings.
Unfortunately, it looks as though word is out on the A-DATA Vitesta 2GB DDR2-533 (ELJKD1A16K) kit – now that it’s back in stock at Newegg, the price has jumped up to $215 (when it was out-of-stock a few days ago, the price was only $150). Oddly, that’s the same price as the faster A-DATA Vitesta 2GB DDR2-667 kit after rebate (ADQPE1A16K)
Regarding the NBCC/strapping issue - okay, it looks as though a E6400 run with a 7x multiplier won't perform as well as a E6300 at it's own native 7x multiplier. OTOH, I'm not seeing many people benchmarking the E6400 with a reduced multiplier anyway (though some have).
Based on the responses I've gotten on four different overclocking forums, I'm thinking that, for me, the E6400 with Corsair XMS2 PC6400 memory (5-5-5-12 @ 1.9V) is the safest bet for a solid overclock on air.
I found the information below interesting though. What's with the variety of DIMM's all using the same IC's ("ProMOS 667MHZ, CL5, 0.09u 64Mx8 ETT" ) ? Why pay extra for the 6400C4 when the cheaper standard 6400 uses the same IC's - is there any difference?
Value Select Modules Value Select modules are built with RAMs that are procured at the wafer level and are packaged and tested to our specifications. As such, they are not available as individual ICs, only as modules. This approach allows us to ship product with very good performance characteristics, low product cost, and a very low return rate.
DDR2 - XMS XMS, or eXtreme Memory Speed, is the process that Corsair uses to take ICs rated at one speed and verify/guarantee their operation at another speed. Since specifications have not been generated to accurately specify operating parameters, Corsair gives these parts an XMS rating. For example, since PC2400 does not exist according to any valid standards institution, Corsair parts are called XMS2400.
5400C4 CM2X1024-5400C4 XMS5402 v2.10 0628134-2 = Micron, 64Mx8, DDR2-533, CL4, Die Rev D
CM2X1024-5400C4 XMS5402 v5.2 0633071-3 = PCS DDR2, 675MHz, CL 4, 64x8 90nm ETT
CM2X1024-5400C4 XMS5402 v5.2 0633071-5 = PCS DDR2, 675MHz, CL 4, 64x8 90nm ETT
CM2X1024-5400C4 XMS5402 v7.1 0629230-11 = ProMOS 0.09u 64Mx8 ETT Rev E
6400 CM2X1024-6400 XMS6405 v1.4 0606096-2 = Micron, 64Mx8, DDR2-667, CL5, Die Rev D
CM2X1024-6400 XMS6405 v4.1 0609102-1 = Infineon AENEON, Die Rev B, 64M X 8 Rev B
CM2X1024-6400 XMS6405 v4.1 0626413-3 = Infineon AENEON, Die Rev B, 64M X 8 Rev B
CM2X1024-6400 XMS6405 v5.1 0634287-2 = ProMOS 667MHZ, CL5, 0.09u 64Mx8 ETT
CM2X1024-6400 XMS6405 v5.1 0631252-2 = ProMOS 667MHZ, CL5, 0.09u 64Mx8 ETT
CM2X1024-6400 XMS6405 v5.1 0631252-9 = ProMOS 667MHZ, CL5, 0.09u 64Mx8 ETT
CM2X1024-6400 XMS6405 v5.1 0633171-6 = ProMOS 667MHZ, CL5, 0.09u 64Mx8 ETT
CM2X1024-6400 XMS6405 v5.1 0629230-7 = ProMOS 667MHZ, CL5, 0.09u 64Mx8 ETT
6400C3 CM2X1024-6400C3 XMS6403v1.1 0619028-4 = Micron, 64Mx8, 2-667 CL5, Die Rev D [/B]
6400C4 CM2X1024-6400C4 XMS6404 v1.1 0626099-3 = Micron, 64Mx8, 2-667 CL5, Die Rev D
CM2X1024-6400C4 XMS6404 v1.2 0620097-1 = Micron, 64Mx8, 2-667 CL5, Die Rev D
CM2X1024-6400C4 XMS6404 v2.1 0635221-22 = ProMOS 667MHZ, CL5, 0.09u 64Mx8 ETT
6400PRO CM2X1024-6400PRO XMS6405v1.1 0610028-1 = Micron, 64Mx8, DDR2-667, CL5, Die Rev D
CM2X1024-6400PRO XMS6405v3.1 0609115-2 = Infineon AENEON, Die Rev B, 64M X 8 Rev B
CM2X1024-6400PRO XMS6405v1.3 0610028-1 = Micron, 64Mx8, DDR2-667, CL5, Die Rev D
8500C5/C4 CM2X1024-8500C5 XMS8505v1.2 0620114-1 = Micron, 64Mx8, 2-667 CL5, Die Rev D
CM2X1024-8888C4D XMS8804v1.1 0634174-2 = Micron, 64Mx8, 2-667 CL5, Die Rev D
