My problem now is that my rigs will not work any of the X1 slots with any bios except for the stock one.



And just so others know, by switching just 3 of 5 cards to a 1.09V BIOS instead of the stock 1.25V BIOS my power draw went down almost 250W.  I was pulling 1250-1275W before and now it pulls 990-1010W.


Others have posted that going from 1.25V to 1.15V saves about 50W.  So going from 1.25V to 1.09V saves around 83W.


Seem right?

All of my cards are the same brand and model.  They are all Sapphire 7950's.  The 20G model.

Which one card are you talking about? The one that is on the PSU with the 3 with the new BIOS?


Just to ease confusion the rig I was talking about that's drawing less power has 5 cards.  All the same.  4 are on one 1200W PSU and 1 is on a smaller 700W PSU.  3 of the cards have the BIOS you linked me to and 2 of the cards have the stock BIOS.

The 3 cards that have the BIOS you linked me to are on the 1200W PSU.

Figured out the power issue.  It was because all of the cards were running at 1.25 V.


Right now I have 4 cards hooked up to the 1200 W Silverstone Gold PSU.  3 of the cards are on the BIOS you gave me running 1.09 V, and one cards has the original BIOS running 1.25 V.



That is drawing 970-1000 W.   It was drawing 1200 W or so before with all of the cards running 1.25 V.



Seems like that was the problem?

Yea I dunno whats going on.  Most of my cards (I have 13 of them) will mine with that BIOS just like they did before I flashed them.  But a few of the cards will not go over 450 KH/s (compared to 625ish KH/s) with that BIOS.


Another thing is that my two 5 card BAMT rigs will run the cards with the new BIOS in the x16 slots, but if I put a card with that BIOS in either one of the x1 slots it wont boot.  I tried jumping the presence pins and no luck.


I dunno what the deal is.  I may try another BIOS.

I flashed a few cards to that BIOS you linked me to.  I did it to 2 cards and they worked fine.  They mine fine and show the lower V.


But the third card I did doesn't work right.  The flash completed successfully and GPUz shows the correct new BIOS.  But when I mine with it it only get 400 KH/s.  I am using the same settings.  If I flash back to the OEM BIOS it will mine 620 KH/s.


You ever had this happen?

I'm not having a 20 amp breaker put in.  I'm having 2 220 V breakers/outlets put in.  If it was just switching a breaker I would do it myself.

I got it figured out.


I flashed the BIOS on one of my Windows cards.   On Trixx when I click default on the OC panel it gives me a default V of 1068.


The BIOS you linked to that I downloaded is 1067.  But even if that's the real stock V then I dunno why my BAMT rigs default to 1.25

Yea now both rigs are doing it.  It's driving me nuts.


I tried restarting the mining and cold reboot and unplugging them and resetting CMOS and everything. I even let it run like that for like 30 mins and its just 0 load not the GPUs.

I will try once I get this other stuff figured out.   Now got dif prob.


Shut down one of the BAMT rigs to turn some stuff off in the bios.

Did it, started it up and it was mining fine.

I turn the second rig off and do it and then when I start it back up it mines but very slow and the load on the GPUs is mostly 0.  It will jump up to 99 or 100 for just a sec on one GPU but for the most part the load is 0.


I'm getting like 800 KH/s between all 5 cards obviously because there is no load being out on the GPUs.


I put the bios back to default.  I tried clear CMOS.  I even tried a fresh BAMT install on a different USB stick.


Nothing else has changed.  I know BAMT will act like its mining if it has no Internet connection but the KH/s will be 0.

It's mining a little but there is just no load being put on the GPUs .  I tried to do the GPU_MAX_ALLOC thing too.


Ever saw BAMT do this before?

When I tried to flash to that BIOS I got an error that said "SubsystemID Mismatch".

Do you remember what your V was with that one?

Yea I have a Sapphire 21196-00-20G.

I have looked at all of the Sapphire 7950 BIOSs before.

http://www.techpowerup.com/vgabios/index.php?architecture=ATI&manufacturer=Sapphire&model=HD+7950&interface=&memType=&memSize=


Can I use any of these BIOSs?  I don't see anywhere where specific model #s are mentioned.

I need to find me a BIOS then.

So then 1.25 is the stock V?

Well I tried to set the V on my BAMT rigs.

I used the --gpu-vddc 1150 but it will not do it.


Still says the cards are running at 1.25V.

So I just noticed another thing.


I dunno why I thought I had the rigs running the cards at 1.15V.  But I just logged into mgpumon and saw that both rigs are running at 1.25V.

I'm probably wrong but isn't the difference between 1.15V and 1.25V something like 50W per card?

Was hesitant to mess with the rigs because they have been running strong for a couple days but today on one of the rigs I put 4 of the 7950's on the 1200W PSU and I left just one 7950 on the other PSU.


I have the kill a watt hooked up and it is reading 1250-1275 W.  I dunno how long it will last or if it is gonna turn off but if it runs like this that means its drawing nearly the same amount of power from 3 7950's as with 4 7950's.   It has been running for about an hours right now.


I guess I will see how long it lasts.





But about how the two PSUs are wired together.  I ran the rigs at first with just a paperclip jumping the second PSUs on pin (green to black).  Now I have them wired together but both ways it was/is drawing the same amount of power.

But either way this thread is pointless.


What I dont think alot of people understand is that shit will work without powering the risers most of the time.  The whole point in powering the risers is so that after you run the rig 24/7 forever the mobo doesnt burn out from pushing so much power for so long.


The motherboard is not designed to be run at 100% load 24/7.  If you do some searching on here you will find people who have had theyre ATX 24 pin connector blow and turn black.  Or other parts on the mob will blow.

Might be wrong but pretty sure that:


The GPU is powered from the PSU plug.


But the RAM on the card is powered from the PCIe slot (ie the mobo).


That's why LTC mining needs risers more than BTC mining.  LTC mining uses the GPU RAM more.

Whoa.  I don't understand any of that.


I do have the PSUs wired together correctly now. (I think)


I used this guide.

http://www.burningissues.net/how_to/power/adaptor.htm