Comparing Memory Bandwidth: UNBuffered Memory Performance

In our article, 'Searching for the Memory Holy Grail — Part 1', we demonstrated that the UNBuffered SiSoft Sandra Memory Test correlated very well with MemTest86 bandwidth results. With all of the Buffering techniques disabled, scores are much lower — sometimes a 50% drop — than the scores you are accustomed to seeing for Sandra Memory tests. However, the unbuffered scores have proven to be a very sensitive measure of memory bandwidth. Regarding memory performance, we will be looking at the maximum stable overclock for the memory and the SiSoft Sandra UNBuffered Memory Test.

The idea of the UNBuffered Memory Benchmark is very simple — you merely turn off all memory buffering techniques. Sandra makes this very easy to do. Select 'Memory Benchmark', right-click 'Module Options', and uncheck the nine boxes that are related to buffering.




Please keep in mind that the Crucial DDR333 modules using Samsung memory are single-sided DIMMs. As we illustrated in 'Searching for the Memory Holy Grail — Part 1', the performance of two SS modules is lower than the performance of two DS modules in 875/865 boards, and cannot be directly compared.

All memory tests were run on an Abit IC7, Intel 875 Canterwood motherboard with BIOS revision 1.5, and a 2.4C Pentium 4, 800FSB processor that has reached 290MHz (1160FSB) on this motherboard.


Crucial DDR333 Samsung SS Performance
Intel 875 Chipset, Dual-Channel, Maximum Overclock
DDR Memory Speed Memory Timings Memory Voltage
(vDIMM)
UNBuffered
Sandra 2003 Memory Test
(MB/Second)
450 Maximum SPD
2.5-7-4-4
2.7V 2472 INT
2460 FLT
460 3-8-4-4 2.8V 2436 INT
2527 FLT


Given the ability of this Samsung memory, rated at DDR333 or DDR400, to reach DDR460 at 2.8V, we can fully understand why OCZ chose this as their base memory chip. However, as good as this performance is, it does not match the specified performance of OCZ 3700 GOLD of DDR466, 2.5-7-3-3, at 2.65V. So how does a manufacturer of high-speed memory get from this base performance to the performance of 3700 GOLD?

Lasering for Heat Dissipation

When information about OCZ using Samsung TCB3 chips for 3700 GOLD first appeared, others were asking the same question we were asking: how did OCZ get a memory rated at DDR333/400 to the performance levels of 3700 GOLD — or did they?

All memory manufacturers (as well as CPU and chipset manufacturers) "bin" chips. This means that they sort chips by speed capabilities. The top-performing chips are then used in the highest-speed products — the rest going into lower rated products. OCZ explained that, in addition to speed binning, they laser the chips to improve heat dissipation before sorting, using the best chips for OCZ 3700 GOLD. They also released an internal document describing the lasering process and how it improves heat dissipation. The information below is from the released internal document:

"INTERNAL USE ONLY : ENGINEERING DEPT -TW-CA

Thermal modification of standard DDR DRAM TSOP packages , for increased thermal dissipation and speed reclassification.

Note #1 : Reference EL DDR packing specification is linked at /spec/elddr.html

Purpose : Increase speed of ( SEC packaged ) TSOP , through using EL DDR packaging theory. To fill product shortage during die revision change

EL DDR Packaging : by decreasing the thickness of encapsulate (low thermal transfer rate ) we are able to effectively increase heat dissipation in DRAM and thereby increase the effective speed of each IC . Using a third party fabrication and packaging plant this theory has been proven and the (B) die revision OCZ EL DDR die had great success. Average maximum speed increase during stage 2 testing has been verified over 23 MHz.

Proposition: While dies fabricated by 3rd parties for OCZ in 3rd party packaging have proven successful to this point . We feel that to insure our success we should supplement by speed binning large quantities of 3rd party IC's and by physically modifying the package decreased thermal resistance and re-speed grade the ICs using the standard Advantest ATE.

Industry Disclosure: See Ryan Petersen

Process Engineering : See XXXXXXXXX

Process Overview :

Samsung semi will provide die location information , we will be using the DP-7 CO 2 laser to remove the surface material from the package face only average laser cut depth is 7mill . After surface removal the package should be sent to ISE for environmental test and then re-speed graded after speed grade and classification chips will be marked ( standard process) and standard process thereafter."


A Closer Look Testing the Process
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  • MS - Saturday, August 9, 2003 - link

    That was my point, unless you test exactly the same samples before and after, there is no significance at all.

    There is also no difference between laser-blasting off the top layer and mechanically grinding it down. I went to the point of where the die itself was shining through the remains of the top layer, you can't go thinner than that and the process is much more precise than laser blasting and guess .... there was not a single MHz that was gained.

    The methodology used here in this review is based on blind faith that all chips were random samples out of the same pot but they weren't. Neither random nor from the same batch and that's why the conclusions fall, at least in my opinion on their face.

    There is another reason for the blasting but that one I can't talk about.

    http://www.lostcircuits.com/memory/sanded/transpar...

    You can see the leadframe with the 66 TSOP legs, and the bondwires that run from there through the package to the bond-pads on the die in the center.

    I went to the point of removing the top layer completely and even got myself some Open-top chips at some time in the past to try all those things and ... guess what again... :)
  • Anonymous User - Saturday, August 9, 2003 - link

    come on, you dont really believe this laser BS do you? you either dont know $hit about memory or you wanna help ocs in some way because you guys personally like them.

    you think those memory sticks you got proove anything? they just gave you a stick that clocks lower saying this is what its before me lasered it and a better clocking stick and say this one is after we sent this stick to space where some ocz bacterias change the molecular structure of the memory chips, and you believe it?

    COME OOOON!
  • wixt0r - Saturday, August 9, 2003 - link

    #25: Give me a break. Wesley Fink (AKA Prometheus) is an excellent hardware reviewer who has put in more time and effort into the community than you will ever do in your lifetime. His reviews and opinions are unbiased, just, and straightforward. The fact that he was hired by Anandtech only proves his worth to the hardware enthusiast community.

    And fact is, OCZ has indeed changed. Evan wouldn't be saying so if he didn't believe it... Maybe you should bash on him while you're at it, he seems to be defending OCZ here, also.

    And the OCZ representitive on ABXZone and Xtremesystems (Ryan Peterson) is very helpful. He's kind, courteous, and always willing to lend a hand. He helped me RMA my 3700 Gold that wouldn't do DDR500 when they aren't even rated for it. That's customer service and satisfaction right there. I doubt he'd ever come to AT because nobody in the forums accepts self-promoters regardless of company, let alone OCZ, where people such as yourself would flame and bash even if comments and posts were helpful and informative.
  • Anonymous User - Saturday, August 9, 2003 - link

    The point about OCZ infesting AT was in regards to them buying praise over on ABX, and now they have an ABX "writer" here pimping this stuff barely 2 weeks after his arrival.A sad day for objective reviewing.

    And OCZ has NOT changed. Reputable companies don't remark parts with their own fake timings. The only thing they've done is install some shills on the noob-centric forums to cater to the people who have no clue what they're doing. I'd like to see them try it on AT Forums, the destruction would be quick and hilarious. That little fact alone should tell you who OCZ's target market is-idiots.
  • Anonymous User - Saturday, August 9, 2003 - link

    #18, my board is an MSI Neo2 LS. Not sure which revision, but I have the latest bios. Got OCZ b/c a review somwhere stated that Corsair, which I usually buy, didn't work well. As it turns out that was not the low latency version. I like the board a lot outside of the memory issue. Heck, the copper jacket on the memory is pretty cool too.
  • Evan Lieb - Saturday, August 9, 2003 - link

    #20, our experiences with the modules OCZ sent us have already been confirmed by users who have bought those same modules retail from online stores such as Newegg, Googlegear, etc. We certainly take that information into account, don't worry. :)

    #22, OCZ has changed for the better. Perhaps you should try out some of their modules?
  • Anonymous User - Saturday, August 9, 2003 - link

    I hope all of those who thing OCZ has suddenly repented of its entire history will come back here and elsewhere and tell everyone they can about their experiences. I think we'll be seeing lots of surprised and disappointed people.

    If they really wanted to change, they'd get a new name, and have no relationship with the old criminals.
  • Anonymous User - Saturday, August 9, 2003 - link

    Where is this memory currently in stock? I'm willing to pay quite a lot for it, in fact.
  • Anonymous User - Saturday, August 9, 2003 - link

    Anandtech should purchase and test this sort of product from various retail locations to get a good feel for what the enduser will receive. It's all too easy for OCZ to send AT a statistical outlier but cash in on the good reputation it builds for their entire product line. In fact, I'm still skeptical. Memory chips don't even get that hot - I didn't think they were as sensitive to temperature as CPUs. Or at least that was the opinion shared by several knowledgeable engineers on the forums here a year or two ago when those RAM sinks started to get in vogue.
  • Anonymous User - Saturday, August 9, 2003 - link

    #14 this is the first OCZ review ive ever seen on AT. Where is the other garbage that is infecting the website?

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