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I've noticed on my 6950 miners, running poclbm without -v -w128 gives about 10% lower hash, but significantly reduces the heat output.  This is helpful to keep my workshop under 100 F during the hottest part of the day (highs around 100 F most days), because I have 8 miners going and two 12,000 btu air conditioners, which is the max air conditioning I can feasibly install.

I haven't calculated the heat reduction, but I think it is about 20%.  Does anyone have accurate numbers from testing different command line arguments v. heat exhaust?

I'm also thinking about returning all cards to stock clocks.  Most are already at stock clocks, which reduced heat alot.  The real question is whether you get a better heat reduction from no arguments or stock clocks.  That way I can choose between increasing hashrate via overclocking or increasing hashrate via -v -w128.  10% higher clock = ? higher heat v. -v -w128 10% higher hashrate = ? higher heat.

 Even at stock core clocks, I would still lower the memory to 300.

I wish I could.  I can lower mem clocks to 300 with MSI afterburner on my 5830 but not my 6970 or 6950 cards, can't find a program to support it.

http://www.sapphireselectclub.com/ssc/TriXX/TriXX.aspx

Trixx buddy, that's the program for your 6970 and 6950 (leave afterburner for the 5830)

















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TRIXX doesn't work for my 6870. Card won't go lower than 800 for mem, and it runs slower at 800 mem vs 1050.

Try lowering the clock, applying the settings, and then closing and reopening the program. This allows me to lower the clock even further.

Why would you want to lower the clock ... other than to reduce heat by dropping your speed?

Also, which clock?  Core or Memory?

EDIT:  I hate my 6950s.  They run hotter than all my other cards and are a royal pain to keep stable at the higher end of overclock.  My 6870s were a better investment.

I've scoured the forums for info on how to use Trixx across 4 gpus or trixx with multiple gpus and found not one answer.  Trixx only sees the first gpu afaik.

I can't find anything to work with my 6870 either.  It's quite frustrating because I would love to lower my mem to 300 just for the temperature.  However, at 800 mem vs 1050 mem, 800 runs quite a bit cooler, and no slower.  I guess that will have to be good enough until someone solves the 6870 memory not wanting to go lower than 800 issue (unless you lower the core speed to lower than 900).

I ment to say the mem clock, lower mem clock = less heat = more stable core overclock
did you check the settings? I recall seeing a sync box that you can check off, maybe I'm thinking of afterburner

Have you tried clocktweak?

http://forum.bitcoin.org/index.php?topic=9982.0 (http://forum.bitcoin.org/index.php?topic=9982.0)

As far as Afterburner, I have 2 6950's and a single 6770 in the same box. If I closed afterburner memory clocks would default to stock, but if I lowered card 1 memory clock to lowest, clicked settings and chose card 2, lowered mc, settings, card 1, my mc would let me go lower.

Closing and reopening despite me following the "yes i agree OC'ing may cause my card to fry" would always default to stock.

Make sure you hit apply before closing and reopening the program.

so it's not like you can turn off  -w
even if you dont use -w 128, poclbm will still use -w 256 as default

CMIIW

Install Rivatuner, then use RBE (no need to modify or flash bios) to make Rivatuner work with your 5000 and 6000 series cards. You can also modify the clocks of your other gpus of your multi-gpu system. Unfortunately, Rivatuner can only lower your mem clocks to half of the default clocks. But you can trick Rivatuner to lower the mem clock of your primary card even more by using afterburner or trixx first to lower mem clock then exit, open Rivatuner, detect clocks and Rivatuner will see the lower clock as default. Enable "Apply overclocking at windows startup". Make sure afterburner and trixx are not loaded at windows startup.

Edit MSIAfterburner.cfg:
UnofficialOverclockingEULA   = I confirm that I am aware of unofficial overclocking limitations and fully understand that MSI will not provide me any support on it
UnofficialOverclockingMode   = 2