Bitcoin Forum

When mining on my computer my hash rate is constantly jumping up and down. It will say 380 mhash/s then 40 mhash/s then jump back up to 250 mhash/s. I'm using -v -w128 -f 1 on my 5870. Is there anything I can do to help keep it steady?

if you perform other tasks with this rig then it is normal. If it is idle and show this behavior, it is tricky, i don't know :)

It's idle most of the time. I'll change it to -f 30 if I'm using it but the fluctuation happens no matter what. I'm running Windows 7 64-bit.

what drivers and how much overclock?

I just got the card the other day so I haven't really tried overclocking it much. I'm using the latest Catalyst drivers with my core clock at 900mhz and my memory clocked down to 900mhz.

What miner are you using? The one I use (Diablo-miner (http://bitcointalk.org/index.php?topic=1721.msg21054#msg21054)) shows two speeds - current and average. Average for me (5870, both clocks at 900) is around 343000 and changes very little, but the current speed does vary enormously. I'll swear I've seen it hit 700000 (and smarter people than me will tell us that that's unpossible... and I suspect they're correct).

At the end of day, average is the only thing that really matters. Even if you miner does briefly go up high, you'll only get a momentary benefit from it. Average tells you far more.

If the card is running too hot it will throttle itself, resulting in a fluctuating hashrate.  I have observed this with 5870s with inadequate cooling bouncing between ~320Mh/s to ~220Mh/s after they heated up.

Overdrive is showing 69-71C. My average on bitcoinpool usually shows around 250 mhash/s. I'm using poclbm-mod.

69-71 degrees should be fine - mine normally sits in the high 70s (according to aticonfig).

I'll try and keep an eye on my hash rate, and see if I notice the same kind of variation.

My brother has a simmilar issue aswell!, although he's running a 5770, his mhashes randomly drop down from 160-50, then when he ends iexplorer it goes back up. Weird eh?

(win 7 64bit ultimate)
I definitly agree with LMGTFY, although i agree with both of his sides, The card shouldn't throttle when around 70° or even 80°, My 6870 Throttles at 110° and auto shutdowns at 120° to prevent heavy damage

Whilst i mine i maintain a steady 75°, with my fan manually set to 75%

I think it might be related to the latentcy I have on satellite interwebs and getting new getworks.

It happens to me when I watch videos in my browser at youtube or other sites.

Just got a new 5870 and the same thing was happening to me.  Apparently I didn't have the most up to date poclbm.  Updating it made it much more stable at 340 Mhash/s with -v -128.

Well most recent poclbm is not our issue, i can cockly assume that everyone's upto date

I found setting the priority of the GPU miner exe's to AboveNormal helped a lot.

But you will always see fluctuations when your actively using your comptuer for other things.

In windows? How do you do that?

1. Open TaskManager
2. Processes Tab
3. Right-click the process
4. Set Priority to AboveNormal

Thanks for the information!
Is there any other way of keeping the rate steady?

FIXED!

The -a flag was what I needed. The satellite lag was messing with the getworks. Instead of the default 5 I moved it up to 8. It is sitting at a steady-ish 330 Mhash/s.