[QUOTE=LaurV;363363]From former discussions I remember that GPUProcessSize of 24 has a chance in 6 to miss a factor, I think you should use 16 or 32. I use 16. The only parameter which seems to influence the speed is the VectorSize (correctly set to 2 for GCN cards, the default of 4 is much worse). Also, primes, I go by the default 84486, but there is not much speed difference between 60, 80, 100k. I go by GPUType=GCN, but it does not really matter for speed, assuming it is AUTO and correctly detected as GCN.

What really makes a difference: go to the "performance" tag in the CCT and set the Overdrive/Power Control to about +15%, otherwise the card will try to keep the power consumption "in check" and throttle after few seconds (it shows that the GPU is used 99%, but in reality is only used 60-70%, the rest is throttling). For me, with 0% (or even +5%) it starts with almost 1T, but back off to ~600G in the first ~5 minutes. When I set it to +10%, still backs off after a longer time. With +15% it continues to run max speed. Of course, this means you need to properly cool the cards, but my AMD cards are air cooled too (I mean, they are not water cooled, only for the gtx stuff I use water cooling).

About the second slot, the card works on in x8 or even x4 slots, as mfakto does not have big traffic. You can check the bios, maybe the slot has strange settings there (different features disabled?).[/QUOTE]


Thanks for the reply.

I've adjusted power setting to +15% but so far I can't see any improvement.

I've also adjusted GPUProcessSize to 16. It's auto detecting GCN aok.

Yeah I have a feeling there's something funky in the motherboard. I'm sure I've read somewhere where these slots had issues with GPUs.

-- Craig

[QUOTE=nucleon;363360]It seems the other pci-e slot isn't suitable.

It doesn't work quite well - speed per gpu drops to 150Ghz-d/day. (Typical is 325-340GHz-d/d)

I've installed msi afterburner to get better details on speed.

It seems it's running at defaults 950core, 1500mem.

Here is the ini file. I'm open to suggestions.

-- Craig[/QUOTE]

Do what I did. Use a ribbon cable to connect the second GPU to the MOBO and hang the GPU outside the case.

Craig: It could be that PCI-E 2.0 x4 is just not enough to feed two HD 7900 chips. People have shown that PCI-E 3.0 x16 or x8 has had extremely little impact in most applications, but 3.0 x8 is four times the bandwidth (and you have two chips going, to boot)

I haven't noticed any decrease in performance either since I added a GPU, which caused a switch to x16 to x8/x8

mfaktc/o does not care about PCI bandwidth. LL tests may, I'm not sure.

Hmm... possible GPU mismatch for [URL="http://mersenne.org/report_exponent/?exp_lo=37631929&exp_hi=&B1=Get+status"]37631929[/URL]. Anyone want to TC?


M( 37631929 )C, 0x149e74d21e55____, n = 2097152, clLucas v1.02

[QUOTE=kracker;363890]Hmm... possible GPU mismatch for [URL="http://mersenne.org/report_exponent/?exp_lo=37631929&exp_hi=&B1=Get+status"]37631929[/URL]. Anyone want to TC?[/QUOTE]

Submit your result, and I'll TC with a CPU.

[QUOTE=chalsall;363891]Submit your result, and I'll TC with a CPU.[/QUOTE]

Done. :smile:

[QUOTE=kracker;363892]Done. :smile:[/QUOTE]

Thank you. :smile:

This candidate is now on one of my machines.

Edit: ETA ~24 hours.

[QUOTE=chalsall;363895]Edit: ETA ~24 hours.[/QUOTE]
:whistle: This guy has half of the computing power in the country... even if that country is so small as Barbados, how can we compete with him? :shock:

Just remind yourself that it's a cooperative venture not a competitive one, and then focus on the lines of people you can beat. :-D

That was a trap post, I expected him to jump and say "no, I only have 6 computers" (which he said somewhere already, talking about those servers), and then I would come and say "yes, that is what I said, half of that country's computing power" :razz: