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Number crunching :
AMD, un-/ganged, what's faster at S@h ?
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Author | Message |
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Sutaru Tsureku Send message Joined: 6 Apr 07 Posts: 7105 Credit: 147,663,825 RAC: 5 |
Hello community! :-) At AMD systems, you can choose un-/or ganged system RAM mode. What's faster here at SETI@home? At CPU WUs.. At GPU WUs.. (because the system RAM is also important for CUDA, faster system RAM -> faster CUDA) Someone made a test? Thanks! |
Fred J. Verster Send message Joined: 21 Apr 04 Posts: 3252 Credit: 31,903,643 RAC: 0 |
Well that is some word, I've never heard. Ganged v.s. UN-Ganged Do you mean 1 or 2 (or3) channel, ERROR Correction? Ganged Memory. Ganged Memory. Anyway, here's something to read :-) Keep on CRUNCHING |
Fred J. Verster Send message Joined: 21 Apr 04 Posts: 3252 Credit: 31,903,643 RAC: 0 |
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ML1 Send message Joined: 25 Nov 01 Posts: 20147 Credit: 7,508,002 RAC: 20 |
"Ganged" and "Unganged" seems to be a new term on some recent motherboard BIOSes. On mine, the help for that option claims that "Unganged" gives higher performance. Now, can anyone explain the technicalities please? Happy crunchin', Martin See new freedom: Mageia Linux Take a look for yourself: Linux Format The Future is what We all make IT (GPLv3) |
razamatraz Send message Joined: 23 Oct 07 Posts: 142 Credit: 27,815,748 RAC: 0 |
The way i understand it both are technically multi channel modes. These only apply to multi core machines...in ganged mode all processor cores have direct access to all memory, in nonganged the cores split up which memory addresses tehy have direct access to...I've also heard that nonganged allows for different memory timings on different slots. There is a lot of confusion to the term. Ganged used to mean that a pair of 64 bit controllers could be used together to transfer to memory at 128 bits. http://ixbtlabs.com/articles3/cpu/amd-phenom-x4-9850-ganged-unganged-p1.html |
Highlander Send message Joined: 5 Oct 99 Posts: 167 Credit: 37,987,668 RAC: 16 |
The newer Phenoms have 2 Memory-Controller on the cpu-die. ganged: the memory controller behave like one controller, but with a 128 bit wide data-bus to the memory. unganged: now the 2 controller work independent from each other, but only with a 64 bit wide bus. from what i have read, the differences between this 2 modes are so small (vary in 0.x % area), that not moving the mouse-curser brings u more usable cpu-cycles :-)) - Performance is not a simple linear function of the number of CPUs you throw at the problem. - |
Stephen R Send message Joined: 25 Aug 99 Posts: 56 Credit: 3,736,096 RAC: 0 |
Depends on what AMD chip you are using ... Basically Phenom and Phenom(II) work best with 2GB sticks and unganged X2 work best 1GB sticks and ganged Not much difference between ganged and unganged unless you are over clocking then it helps quite a bit with stability |
TheFreshPrince a.k.a. BlueTooth76 Send message Joined: 4 Jun 99 Posts: 210 Credit: 10,315,944 RAC: 0 |
Ganged mode gives me 10 minutes faster crunching on avg. 2:00 vs 2:10 ... Rig name: "x6Crunchy" OS: Win 7 x64 MB: Asus M4N98TD EVO CPU: AMD X6 1055T 2.8(1,2v) GPU: 2x Asus GTX560ti Member of: Dutch Power Cows |
Sirius B Send message Joined: 26 Dec 00 Posts: 24877 Credit: 3,081,182 RAC: 7 |
That caught me out when I built new rigs recently with Athlon II/Phenom II quads. It's just AMD trying to differ from the mainstream: - Single vs Dual channel. |
Sutaru Tsureku Send message Joined: 6 Apr 07 Posts: 7105 Credit: 147,663,825 RAC: 5 |
Thanks to all for replies! I looked a little bit around.. At least for Phenom II CPUs: If you have un-/or ganged mode, you have always dual-channel. Unganged mode could give improvement at multi-thread apps. Ganged for single-thread apps. AFAIK, S@h have single-thread apps, so ganged mode could/should give more performance. I have since a few hours unganged mode in BIOS disabled. CPU-Z show ganged mode and dual-channel. If the Inet connection of SETI@home is again enabled, after a few hours (the last time ~ 5 hours) the results of 3 days are all UL/reported, I could see if this help. Maybe this is the AMD trick for to beat the Intel's.. X-D (Because they are always bullied from Intel..) |
Sutaru Tsureku Send message Joined: 6 Apr 07 Posts: 7105 Credit: 147,663,825 RAC: 5 |
Hmm.. strange.. After a few hours in ganged RAM mode, my machine made an auto reboot.. I changed only the RAM slots from #1 + #4 to #1 + #2. I read about that I should use the first slots of each channel. And I disabled the unganged RAM mode, for to have ganged RAM mode. That was all. If I get again an auto reboot, it's the RAM slots, or overheat of the RAM, because now they are very close.. They are 2x 2 GB OCZ DDR2 1066/5-5-5-18 @ 1.8 V (low voltage) RAMs (OCZ2P1066LV4GK).. maybe little buggy..? :-/ [EDIT: Ahh.. BTW.. I'm back to unganged.. for to test if again an auto reboot..] |
Stephen R Send message Joined: 25 Aug 99 Posts: 56 Credit: 3,736,096 RAC: 0 |
Yes you should have (assume 2 x 2GB sticks) one in first slot for channel 0 and one in first slot for channel 1 Which slot is which depends on the MB .. and a lot of times the manual for XYZ MB is wrong as to which slot belongs to which channel. (my MB manual shows slots 1 and 2 as channel 0 and slots 3 and 4 as channel 1 .. which is wrong ... in fact it is slots 1 and 3 on channel 0 and slots 2 and 4 on channel 1 ... so double check) So I have 1 x 2GB stick in slot 1 and 1 x 2GB is slot 2 ... being 1 2GB stick for each channel ... and run as unganged. OCZ is normaly pretty good memory. I assume you are showing memory as 1066 in CPU ID .. meaning Dram Freq. shows as ~ 533mhz, type DDR2 and channels # as dual. You may want to consider bumping your memory voltage up a small amount to say 1.95v as that can help, it did with my Phenom running OCZ memory For stability in the end with my Phenom II X4 940 I found running unganged was best with a bump in memory voltage to 2.1v, a little looser memory timings with the memory set to run as 535mhz to get 1066 dual channel (this is with Corsair memory not OCZ). |
Sutaru Tsureku Send message Joined: 6 Apr 07 Posts: 7105 Credit: 147,663,825 RAC: 5 |
I have a MSI K9A2 Platinum, which was for ~ 2 years the only mobo with 4x PCIe 2.0 x8 slots (max CUDA performance).. :-) So I could add 4x GTX260.. On mobo I see DIMM #1, #2, #3, #4 - from left to right. And channel one and channel two with different colors. #1 #3 channel one and #2 #4 channel two. So the RAMs are in #1 and #2. Yes, they are as 533.x MHz in CPU-Z. On the OCZ RAMs is a sticker with @ 1.8 V. On the OCZ site (OCZ2P1066LV4GK. AFAIK no longer available for to buy - so I need to take care ;-) stay, OCer can use 1.85 V (this is meant with EVP ?). I read in the internet about that some gave 1.9 V and they were cooked/damaged. But I don't know if this is true.. you can read a lot of nonsense in the internet.. ;-) I ordered inter alia 3x 40x40x10 fans for to make my own active RAM cooler. If installed, maybe will test the 1.85 V and ganged RAM mode. Maybe with littel bit more V the ganged RAM mode work? I read also about, that if you have a Phenom II X4 you should not use more than 1.8, or 2.0 V at the system RAM - depend where you read.. If > 1.8 V (2.0 V) you will cook/damage the integrated memory controller of/in the CPU. I looked at the AMD site, but didn't found infos about, but maybe I looked not at the right places. What you (all) think about? |
Stephen R Send message Joined: 25 Aug 99 Posts: 56 Credit: 3,736,096 RAC: 0 |
EVP = enhanced voltage protection ... fluff? in any case because of the RAM warranty don't set ram voltage higher than 1.85v. with regards to the ganged and unganged, relative to memory channels on my X4 940 and my MB I have found the following. With 1 2xGB stick in each channel (meaning slots 1 and 2) ganged (synthetic 128 bit path) would run ok for awhile but every so often there would be an "auto" reboot ... unganged (64 bit path) did not have this problem. From talking to the memory guy (a back roomer eng.) it was suggested that ganged would possibly work ok with both 2GB sticks on the same channel (however most MB don't like this for dual mode) ... but that it was better to utilize 2 channel at 64 bit rather than 1 channel as sythetic 128 bit. I did try ganged with all 4 slots filled (all be it with 1GB sticks) and stability was worse (of course a lot of that has to do with the memory / MB / CPU combination) What I was lead to believe in the end was that the X4 940's on chip memory controler left some things to be desired. So I decided just to be happy with unganged mode, memory running at 1066 and no out of the "blue" re boots |
Sutaru Tsureku Send message Joined: 6 Apr 07 Posts: 7105 Credit: 147,663,825 RAC: 5 |
Hmm.. strange, why the memory guy say 2x 2GB RAMs (each channel) and ganged will work and it don't work..? Hmm.. maybe 64bit OS? ------------------------------------------------------------ IIRC, MaGNeT (a.k.a. BlueTooth76) have a Phenom II X6 and ganged work on his system. Please give your system specs - CPU, mobo, RAM, voltages? And you never see reboots or something similar? |
Jim_S Send message Joined: 23 Feb 00 Posts: 4705 Credit: 64,560,357 RAC: 31 |
I'm getting ready to build a Win XP 32 bit system like this; Athlon II X4 630 (4 x 2.8GHz - 2MB Cache - 4000MHz FSB) Gigabyte M68M-S2P/W (2) DDR2 800 1 Ghz KHX6400D2LLK2 Ram. Should I go with Ganged or Un-ganged? I Desire Peace and Justice, Jim Scott (Mod-Ret.) |
Sirius B Send message Joined: 26 Dec 00 Posts: 24877 Credit: 3,081,182 RAC: 7 |
I'm getting ready to build a Win XP 32 bit system like this; That's not a bad cpu. Built an htpc with one with gigyabyte MA790XT-UD4P mobo for the wife & using ganged mode. Athlon II 630 host |
Karsten Vinding Send message Joined: 18 May 99 Posts: 239 Credit: 25,201,931 RAC: 11 |
My personal experiences with ganged vs unganged is that its easier to get the machine stable in ganged mode. You can run tighter memory timings and also faster memory clocks. This shouldn't be so, but on my system it is. The difference I'm seing between the two in crunching times are very small (with same settings), but the better settings ganged mode allows me to run with, gives me the best crunching times in ganged mode. So my advice is to use Ganged mode. But with other hardware peoble will get other results, so its not easy giving final advice. |
Sutaru Tsureku Send message Joined: 6 Apr 07 Posts: 7105 Credit: 147,663,825 RAC: 5 |
Maybe it would be well to make an overview with systems and if it's possible to let run unganged (standard) and ganged system RAM mode. Maybe then the other could find a way for to optimize their system for un-/ganged RAM mode.. Ganged RAM mode should be faster with single-thread applications (S@h). AMD Phenom II X4 940 BE (standard @ 3.0 GHz) MSI K9A2 Platinum OCZ 2x 2GB DDR2 1066/5-5-5-18 @ 1.8 V (standard settings, low voltage RAM) 4x GTX260-216 (manufacturer OCed) WinXP Home x86 Edition (32bit) Full loaded S@h: Unganged: YES Ganged: NO (auto reboot) (For example: Maybe if I increase the RAM voltage, ganged is possible? ;-) |
TheFreshPrince a.k.a. BlueTooth76 Send message Joined: 4 Jun 99 Posts: 210 Credit: 10,315,944 RAC: 0 |
Maybe it would be well to make an overview with systems and if it's possible to let run unganged (standard) and ganged system RAM mode. Rig name: "Crunchy" OS: Win 7 x64 MB: Asus M4A89GTD PRO DDR3 CPU: AMD X6 1055T 2.8@3.5Ghz (1,325v) Mem: 2x2 Gb DDR3 (Kingston KVR1333D3N9K2/4G) - Ganged Mode CPU COOLING: Scythe Mugen 2 rev.B GPU: Asus ENGTX470 607@780Mhz (stock aircooling & 1.025v) Works both unganged and ganged. Ganged mode is about 4% faster (10 minutes on a WU). Rig name: "x6Crunchy" OS: Win 7 x64 MB: Asus M4N98TD EVO CPU: AMD X6 1055T 2.8(1,2v) GPU: 2x Asus GTX560ti Member of: Dutch Power Cows |
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