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  #1  
Old 04-22-2008, 11:58 PM
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Default Ganged vs. Unganged tests show...

Hey all.
I've just built a new Spider system. So, I've benched the CRAP out of these sticks using Everest Ultimate Memory Benchmark (I know, quick and dirty, but it is quick and gives a decent impression of where my next step in overclocking should be)

Why is it that Ganged *ALWAYS* gives more bandwidth than UNganged with my board and these sticks running the Everest Benchmarks??

The difference is actually quite a bit - about 1000MB/s on READ and roughly 500MB/z on WRITE and COPY, with the latency (ns) being significantly slower using UNganged (i.e. 53.3ns Ganged vs. 57.1ns UNganged)

So, I understand what Ganging actually is - I've read it on at least 6 different forums...but what I don't understand is the numbers that I'm seeing...is Everest just plain wrong? or is there something that I'm missing??

So far, I've tested lots of different combinations of overclock, from low FSB and high CPU multi, to 800MHz RAM with tight latencies to 1067MHz RAM with SPD latencies, to voltage increases and decreases...
I've found that these sticks will boot to Windows at 1175MHz with the NB and HT at ~2400MHz (2150MHz for the HT)

But, I'm having some issues combining it all. I understand the old K8 well.
I had an Opty 165 running at 3.2GHz for over a year on an A8R32-MVP Deluxe with 2 X 1GB XMS3202 v1.3 running at a whopping 583MHz (292MHz), and I also understand the equation for a perfect overclock:

(CPU Multi) * (FSB) = (CPU Freq)
(CPU Multi) / (Memory Divider) = (Divisor Ratio)
(CPU Freq) / (Divisor Ratio) = RAM MHz (* 2 = DDR)
(NB (or HT back in the old days)) * (FSB) = NB MHz
and that the new unlocked HT *has* to always be less than the NB.

So, currently, I've been able to boot to Windows at 2.9GHz (unstable) at 1.3V, 2.8GHz (stable as per Orthos and OCCT for 6 hours so far) with the NB at 2206 and the HT at 2006, RAM at 535MHz 5-7-7-25-31 2T at 2.2V.

In addition to the question on Ganged vs. UNganged, can someone maybe help me get a bit more out of my system?? Again, veteran overclocker and I understand a lot about overclocking...but there's something I'm just not getting here.

Thanks in advance.

Psychlone

Last edited by Wired; 04-23-2008 at 12:26 AM. Reason: removed PC specs; already in dropdown / profile
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  #2  
Old 04-23-2008, 02:50 AM
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The Phenom has two memory controllers on the CPU. Ganged is setting both memory controllers to work together which allows data (that is being used by all cores) to await on the queue until they are accessed. Unganging means that the two controllers work independently. This allows them to work asynchronously with reference to individual clocks with their one or two Dimms. I would set your Quad Core to unganged.

If you want more performance, then run with a two DRAM slot population. Test it out. Remove two sticks and retest. Also, keep in mind that fast and unstable means little and looking at the speed of an unstable system is not a good way to find your sweet spot. I can run my DRAM faster and my system faster by a fair bit, but it will be unstable. It is foolish for me to not accept the limitations that stability sets on my system speed.

I can make 4.0Ghz unstable and 11000MB/s Read with 47ms latencies. Nice but nowhere near stable.

I can make 3.6Ghz stable and 9958MB/s Read with 50.3ms latencies. That's my reality. If I install two more of the Corsair 10000 (1250Mhz) sticks, I lose my 1200Mhz DRAM speed and it has to drop to ~1066Mhz to deal with the memory controller.



Now the AMD Phenom is known to be wonky and higher DRAM speeds. Running with four slots populated is also known to create instability in Phenom when attempting high speeds.

You may wish to research here:

http://www.ocforums.com/forumdisplay.php?f=3
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  #3  
Old 04-23-2008, 10:58 AM
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Thanks for the reply.

I do understand what Ganged vs. UNganged actually is, I've researched the CRAP out of it because I didn't know and had never seen it before this board...but thanks for the info anyway.

I also understand the different between an unstable overclock with killer looking numbers and the reality of the hardware's limits - been doing this for many years, and I absolutely agree with you.

On the part about only populating 2 banks instead of all 4, I've just ordered 2 X 2GB modules of the Dominator 8500C5DF that hopefully will come in as the version 1 - *that* would be nice!!! - but I will give the 2 bank overclock a try.

Thanks for the link - been there, as well as all over the 'net researching...but in the end, I haven't really learned much from other people's experiences since all hardware is not created equal. I know that the same exact stepping Phenom 9850 in the same exact M3A32-MVP revision board that I have will overclock quite differently - some reaching into the 3.2GHz + range on air...stable. But, I also know that doesn't mean mine is going to.

Thanks for the help though - the 2 X 2GB sticks hopefully will help me out a bit.

**BUT - I still can't get it straight in my head why Everest's Memory Benchmark shows higher throughput for Ganged with my setup...shouldn't it be the other way around? Seems like if the memory controllers are independent, that they BOTH could access information at the same time rather than having to wait on a queue, right???
I have run the bench so many times that I'm sick of doing it...and *every* time, it shows UNganged with a lower throughput than Ganged - is this just an Everest error?

Psychlone
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Old 04-23-2008, 02:25 PM
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Thanks for clarifying your question. Sometimes the tree is hard to see for the forest. I agree with you. Unganged not only should be faster, in my mind, it is faster. Ganged mode is 1x128bit dual channel and unganged mode is 2x64 bit dual channel. Most programs that test for bandwidth are not testing Phenom correctly. They are testing with a one threaded algorithmic mode. I'm not sure if there is any program that, at this time tests with a two threaded algorithmic mode. What is confusing for most is that Eversest, Sandra, et al, test with a two threaded algorithmic mode for K8 Dual Core. This serves to really piss off those who have moved from K8 to Phenom and think that their data stream is slower. Also, keep in mind that the Phenom works with just one 64 bit IMC, not two which will be a true unganged mode when the CPU runs with two 64 bit IMC's.

Regarding the two modules of DRAM. When populating with two DRAM modules in Dual Channel, two sticks will scale higher on a board where slot 1 and 2 connect to different channels. Shorter traces mean reduced capacitive loading and possibly lower delays (like Max Async Latency), so with two slots populated it would normally be best to use the slots that are closest to the CPU. However, I believe that your M3N32 has an adjustable "AI Skew" in the BIOS which will serve to compensate for trace lengths.

There's a bit more information here where the same results as you have interpreted has been found.

http://www.hardwarecanucks.com/forum...e-preview.html
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  #5  
Old 04-23-2008, 08:28 PM
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Derek, you're awesome! Thanks for the input.
I understand now that the benchmarks out there aren't really testing both channels as individuals...maybe Everest will have an update for it soon.

And, you're right, the M3A32-MVP BIOS does indeed have adjustable skews...but what's really cool, to my knowledge, any configuration of RAM in any given bank will result in Dual mode. (i.e. bank1 and bank2 or bank1 and bank3 or whatever...) instead of the old way of splitting up the ram into channels (which this BIOS has also)

So, anyway, I've read and read, and tested this RAM ad nauseum (so much so, that I've actually superglued a toothpick to the CMOS jumper to make it quick and easy to clear!!! ;) ) - and I've found that 5-7-5-23 2T at 2.2V seems to work pretty effectively, but I'd really like to dial in this RAM (well, the new 2X 2GB 8500C5Df when it gets here)
A couple things I used to do to attain stability on my 'old' Opty 165 system with the XMS3202C2 RAM was to raise (beyond SPD) the Read Preamble, TREF and ASYNC Latency...then crank up the MHz till it wouldn't POST, drop it down a bit, then tighten everything else up, leaving the Read Preamble, TREF and ASYNC Latency up high (mostly still above SPD - i.e. Read Preamble 9.0ns, TREF at 15.6us, and ASYNC Latency at 10.0ns (maybe I have the ASYC and Read Preamble backwards- I can't remember)
Anyway, what I'm getting at here is that this BIOS doesn't have *any* of those latencies (with the exception of TREF, and it has 4 of them - assumable because of 4 sticks (?) and their values are in the hundreds instead of the tens)

So, what does Read Preamble, TREF and ASYNC Latency translate to with the newer DDR2 sticks??

Thank you again for all the information and help...I really appreciate it!

Psychlone
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Old 04-23-2008, 09:24 PM
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At this point in time, with regards to Phenom and DRAM, you will find Memset to be very useful. There's a new term out there, it's called MOBOSUCK with regards to Phenom and DRAM BIOS settings.



With Memset you can tweak away to your hearts delight but there are many settings that are just not there at this time. Hopefully BIOS updates will deal with this issue.

http://www.tweakers.fr/download/MemSet35beta.exe
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Old 04-24-2008, 12:29 PM
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Alright...I feel stupid now (or had a senior moment - you pick)

Every time you've said Memset in at least 10 threads around here helping others, I've seen "Memtest" and of course, didn't bother downloading it because I already have it.
I ran Memtest through 2 passes overnight when I first got my current RAM just to test stability at 1066...then haven't pulled it back out to test since because I haven't settled on an overclock for it yet.

So, understanding that a lot of options just aren't in Memset, or have different names than in my BIOS, I do notice that TREF is now "Refresh Cycle Time"...but why is it when I set it from 127 (for banks 1&2) and 75 (for banks 3&4 on mine) to 195us, it will not help to increase stability like I experienced on my old A8R32-MVP ?? Granted, TREF was only 1 of 3 things that were loosened to help with a higher MHz, and everything else was tightened below SPD, but TREF so far, is the only latency that I can find that matches the 'old' way - everything else has a different name now.

Is there somewhere out there that has compiled a list of what all the new latencies names translate to? Back in the old days ( ;) ) there was a guide a DiY Street for the DFI motherboard that explained what each of the latencies did - but I can't find it now, *AND* - a bunch of the latency names have changed (along with taking away or adding others, to which I can't find descriptions - I google some and end up with 32 pages of links of others trying to figure out the same stuff!)

Thanks again for the info. I have UNganged my memory and am dealing with the 'apparent' drop in throughput, putting my faith in you (and logic) that UNganged really is faster...(makes sense!)

Psychlone
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Old 04-24-2008, 06:42 PM
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<Blatant Personal Opinion>
It's too bad you decided to go with AMD rather than Intel. There are not many sites with good research on this CPU technology. tREF is the same with Intel and there have been no such changes. I can't really help you much more because I have not worked with this technology. I was running with Athlon when the Pentium 4 Netburst architecture was out because Netburst plainly sucked and at this moment, AMD clearly sucks as well. So you would do better with sites such as www.ocforums.com where there are some who use the same technology. For the life of me I don't know why, but even when Intel sucked large, there were many Intel owners
</End Blatant Personal Opinion>
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Old 04-24-2008, 07:07 PM
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Quote:
Originally Posted by DerekT View Post
<Blatant Personal Opinion>
It's too bad you decided to go with AMD rather than Intel. There are not many sites with good research on this CPU technology. tREF is the same with Intel and there have been no such changes. I can't really help you much more because I have not worked with this technology. I was running with Athlon when the Pentium 4 Netburst architecture was out because Netburst plainly sucked and at this moment, AMD clearly sucks as well. So you would do better with sites such as www.ocforums.com where there are some who use the same technology. For the life of me I don't know why, but even when Intel sucked large, there were many Intel owners
</End Blatant Personal Opinion>
:)

I've been working with AMD since the old Athlon TBird 1700+ (actually before, but it was the 1700+ that really got the overclocking bug in me...what with the tracing l1's with rear-window defogger kits!)

Anyway, the reason I went with AMD, even though I know they're inferior to Intel at the moment, is double sided:
1) If no one purchased AMD because of the predicament they're in, then Intel would have NO competition and would be buttraping us all for their technology - so I'm just supporting the underdog.
2) Deep in the back of my mind, I know that AMD will pull out of this sometime, and the Phenom surely is surely a step in the right direction (for reasons that I just won't go into here - it's not a discussion about semantics) - AND, since I've worked with AMD so much throughout my life, I understand how it works, and quite frankly, learning how to overclock from square one with Intel simply scares the Hell out of me!! ;)

Anyway, thanks again for all the input - I'm a member of at least 6 forums that are overclocker's heaven, and am *very* active at Guru3D...having helped hundreds of people with various issues. The reason I even joined this site is not only because of the intelligent input that people such as yourself have given many others, it's because DDR2 is completely new to me, and I wanted to find more information, preferably from the people who make the RAM.

Again, thank you for all your help, and if you come across some obscure site that happens to have a translation of all these new memory timings, please don't hesitate to pm or email me.

Psychlone
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Old 04-24-2008, 07:25 PM
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Quote:
Originally Posted by Psychlone View Post
1) If no one purchased AMD because of the predicament they're in, then Intel would have NO competition and would be buttraping us all for their technology - so I'm just supporting the underdog.
You're a good man Charlie Brown.
Quote:
Originally Posted by Psychlone View Post
2) Deep in the back of my mind, I know that AMD will pull out of this sometime, and the Phenom surely is surely a step in the right direction (for reasons that I just won't go into here
I agree, they will and when they do I will be knocking on the door once more

Quote:
Originally Posted by Psychlone View Post
Again, thank you for all your help, and if you come across some obscure site that happens to have a translation of all these new memory timings, please don't hesitate to pm or email me.
I most certainly will.
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Old 04-25-2008, 09:06 PM
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Default Update:

Quick update - no reply necessary, unless, of course, you want to... ;)

I just received my 2 X 2GB sticks of Dominator 8500C5DF, and they are version 1.1 sticks!!!!!!! (Whooohooooooo!) - this is me being elated!

Anyway, successful overclock at 2.9GHz with 1.3V VCORE, 2.1V VDIMM at 1067, 5-5-5-15 2T, UNganged

Now time to get cracking out on it again!!!

Psychlone
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Old 04-26-2008, 02:41 PM
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I told you that you would be far happier with 2 DRAM slots populated.

Well done,

Quote:
Originally Posted by Psychlone View Post
Quick update - no reply necessary, unless, of course, you want to... ;)

I just received my 2 X 2GB sticks of Dominator 8500C5DF, and they are version 1.1 sticks!!!!!!! (Whooohooooooo!) - this is me being elated!

Anyway, successful overclock at 2.9GHz with 1.3V VCORE, 2.1V VDIMM at 1067, 5-5-5-15 2T, UNganged

Now time to get cracking out on it again!!!

Psychlone
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