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Number crunching :
How can I crunch on both GPUs in a ATI4870x2?
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Send message Joined: 22 Feb 09 Posts: 20 Credit: 105,156,399 RAC: 0 |
I would like to know if it is already possible to use both GPUs of a dual 4870 ATI graphic card or still not. |
Send message Joined: 21 Feb 09 Posts: 180 Credit: 27,806,824 RAC: 0 |
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Send message Joined: 8 Jan 09 Posts: 58 Credit: 53,161,741 RAC: 0 |
Its possible to crunsh n-WUs on y-GPUs, Gipsel's app 0.19f: - n-WUs (setting n2 = 2WUs per GPU) on y-single-gpu-cards or (y/2) 38?0x2 / 48?0x2 cards or a mix of it: Example: you can crunsh 6 MW-WUs at the same time if you got: a 4870x2 and a 4870 = 3x 4870-GPU and the setting n2 or 3x ATI4870-Cards = 3x 4870-GPU ! current maximum is 4 4870x2-Cards = 8 GPUs, with n2 = 16WUs; with n3 = 24WUs ... BUT: all cards must be active (Monitor or dummy pluged in or Xfire active) REAL EXAMPLE = http://milkyway.cs.rpi.edu/milkyway/show_host_detail.php?hostid=48886 core_client_version>6.5.0</core_client_version> <![CDATA[ <stderr_txt> Running Milkyway@home ATI GPU application version 0.19f by Gipsel allowing 2 concurrent WUs per GPU CPU: Intel(R) Core(TM) i7 CPU 920 @ 2.67GHz (8 cores/threads) 2.67772 GHz (282ms) CAL Runtime: 1.3.158 Found 3 CAL devices Device 0: ATI Radeon HD 4800 (RV770) 1024 MB local RAM (remote 2047 MB cached + 2047 MB uncached) GPU core clock: 780 MHz, memory clock: 1000 MHz 800 shader units organized in 10 SIMDs with 16 VLIW units (5-issue), wavefront size 64 threads supporting double precision Device 1: ATI Radeon HD 4800 (RV770) 1024 MB local RAM (remote 2047 MB cached + 2047 MB uncached) GPU core clock: 780 MHz, memory clock: 1000 MHz 800 shader units organized in 10 SIMDs with 16 VLIW units (5-issue), wavefront size 64 threads supporting double precision Device 2: ATI Radeon HD 4800 (RV770) 512 MB local RAM (remote 2047 MB cached + 2047 MB uncached) GPU core clock: 780 MHz, memory clock: 1000 MHz 800 shader units organized in 10 SIMDs with 16 VLIW units (5-issue), wavefront size 64 threads supporting double precision 2 WUs already running on GPU 0 2 WUs already running on GPU 1 2 WUs already running on GPU 2 No free GPU! Waiting ... 27.8616 seconds. Starting WU on GPU 0 .... |
Send message Joined: 14 Feb 09 Posts: 999 Credit: 74,932,619 RAC: 0 |
With base settings, I crunch 3 at a time on the 4830. |
Send message Joined: 22 Feb 09 Posts: 20 Credit: 105,156,399 RAC: 0 |
Its possible to crunsh n-WUs on y-GPUs, Gipsel's app 0.19f:ยทยทยท If I only have a 4870x2 graphic card can I crunch 4 WUs at a time (two in each GPU) with n2 and the internal Xfire active? BUT: I know that with Nvidia card and CUDA the internal SLI of a dual graphic card MUST BE innactive. |
Send message Joined: 8 Jan 09 Posts: 58 Credit: 53,161,741 RAC: 0 |
yes you can / should be able to do this |
Send message Joined: 25 Mar 09 Posts: 11 Credit: 10,178,231 RAC: 0 |
Is it possible if I add 3870 card into my current 4870 system? I know that they cannot be used to CrossFire each other but what about using dummy plug or monitor? |
Send message Joined: 4 Oct 08 Posts: 1734 Credit: 64,228,409 RAC: 0 |
Is it possible if I add 3870 card into my current 4870 system? I know that they cannot be used to CrossFire each other but what about using dummy plug or monitor? Provided you have empty PCI-E slots, and use a dummy monitor plug, the additional GPU should crunch fine (as I understand it). Go away, I was asleep |
Send message Joined: 21 Feb 09 Posts: 180 Credit: 27,806,824 RAC: 0 |
You can use it without using a dummy plug or a second monitor. Right click desktop -> properties -> settings. Select your second card, click 'Extend the desktop to this Monitor' and 'Make my primary monitor/desktop'. Click Apply, then you have to move your monitor cable over to your second card. Now both will be enabled for crunching. |
Send message Joined: 25 Apr 08 Posts: 19 Credit: 31,151,552 RAC: 0 |
Enable Crossfire via the CCC. I have TWO 4850X2s in one system and they work fine with Crossfire enabled. |
Send message Joined: 26 Jul 08 Posts: 627 Credit: 94,940,203 RAC: 0 |
Enable Crossfire via the CCC. Or to cite one of your WU's task details: CPU time 78.30197 I would think you could gain a tiny bit of performance if you raise the memory clock slightly. It's a 4850X2 with only GDDR3 after all (even on a HD4870 with GDDR5 250MHz reduce the performance by ~5% already). Furthermore, if you enable crossfire the memory contents for the GPUs are duplicated, thus raising the bandwidth requirements. |
Send message Joined: 21 Feb 09 Posts: 180 Credit: 27,806,824 RAC: 0 |
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Send message Joined: 22 Mar 08 Posts: 65 Credit: 15,715,071 RAC: 0 |
Is there any advantage to cross-firing a headless dedicated Boinc cruncher? Would the answer make a difference if matched or unmatched cards? Thanks, just wondering for future purchase decisions. Currently most my experience is with Nvidia cards; in which SLI and Boinc cannot be used together. |
Send message Joined: 22 Feb 09 Posts: 20 Credit: 105,156,399 RAC: 0 |
Now I would like to know whether I shall get approximately the same points/day with a 4870x2 than two 4870 single cards? |
Send message Joined: 21 Feb 09 Posts: 180 Credit: 27,806,824 RAC: 0 |
Is there any advantage to cross-firing a headless dedicated Boinc cruncher? Would the answer make a difference if matched or unmatched cards? Thanks, just wondering for future purchase decisions. Currently most my experience is with Nvidia cards; in which SLI and Boinc cannot be used together. It's easier to set up :) Means you don't have to faff around sorting out the second card to crunch. A matched card makes it a lot easier in my experience. Also, more cores helps for the time being... Now I would like to know whether I shall get approximately the same points/day with a 4870x2 than two 4870 single cards? If you have a second card in the system, you reduce the CPU:GPU ratio, meaning that you have more chances of running out of work. It's the same if you use two seperate cards, or one X2 card, though with two seperate cards if you come across anotehr quad core machine, you can move it over there. I find 2CPU:1GPU a good minimum ratio - a 1:2 ratio means your cache will be sucked try in about 3-4 minutes. I plan to supply my i7 machine with two 3850X2s come pay day... |
Send message Joined: 25 Apr 08 Posts: 19 Credit: 31,151,552 RAC: 0 |
Is there any advantage to cross-firing a headless dedicated Boinc cruncher? Would the answer make a difference if matched or unmatched cards? Thanks, just wondering for future purchase decisions. Currently most my experience is with Nvidia cards; in which SLI and Boinc cannot be used together. Not a problem at all. I have a quad core cpu and I get 24 workunits at maximum. Enough to keep four gpus (with 2 Workunits per GPU) busy. I think you can even go to GPU:CPU ratio of 4:1 with the new MilkyWay_GPU Project because we will get bigger workunits there and I bet even more workunits at a time.... Enable Crossfire via the CCC. Well, two 4850X2's produce a nice amount of heat, and one of the GPUs is at a high temp level. I won't overclock before I get that straightened. Also, I'm going to solder those "vga dummy" devices so I can go without Crossfire in the future so the mentioned bandwith problems are no longer an issue. But thanks for your comments on this. :-) Sysfried |
Send message Joined: 21 Feb 09 Posts: 180 Credit: 27,806,824 RAC: 0 |
You'd be surprised - even with work flowing as it is, I have come across one of my dual cores, with a 4850 running n1 setting, be without a WU for a couple of minutes every so often as it only takes 6 minutes to empty the cache. With a 4:1 on 30sec WUs you'd compute 4 WUs in the first 30s, then end up with 30s with 2 GPUs not working before you could contact the server again. Then you'd only have work for the next minute if you get it. Agreed on the MW_GPU front though - it won't matter then :) |
Send message Joined: 17 Nov 08 Posts: 2 Credit: 33,115,365 RAC: 0 |
Is there any special configuration for the app_info file? Thanks! |
Send message Joined: 28 Jan 08 Posts: 40 Credit: 379,931,801 RAC: 0 |
...... Hi! Just installed a new 4870X2 - I can only get it to run WUs on a single GPU. As it is a dual card Xfire is enabled automatically - can't see any obvious way to disable it - any thoughts? From reading this post it looked as though the X2s would run WUs on both GPUs - well not for me! My appinfo.xml is set up the same way as on a host with multiple cards (which works fine) - is there some trick I'm missing? Thanks, P. |
Send message Joined: 29 Aug 07 Posts: 486 Credit: 576,548,171 RAC: 2,784 |
Pat, Have you Tried using a Dummy Plug yet on the 2'nd half of the Card ... ??? |
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