Hash rate swinging a lot

[iLLmAtiCiAn]

Hey guys, I have two miners where the hash rates stay mostly constant but on one miner the hash rate changes a lot. Gpu utilization keeps going from like 99% to like 80% and all the way in between.

[Bitcraft]

Might be a weak power supply. What are the specs (all of them) for your rig?

[iLLmAtiCiAn]

I don't think it's the power supply unless it's faulty. I have a hx850 powering a 5870 and a 5850 with an amd sempron + 1gb ddr3 ram stick

[iLLmAtiCiAn]

I mean i have an elitexstream 800w powering 3x 5850 just fine on my other rig

[iopq]

what miner are you using? What is the temperature like on the cards?

[iLLmAtiCiAn]

using guiminer opencl, temperature looks fine, it's 78-80 max on 5850 and below 70 max on 5870

[RyNinDaCleM]

In GUIminer, What flags do you use?

[turquoise9955]

using guiminer opencl, temperature looks fine, it's 78-80 max on 5850 and below 70 max on 5870

Could still be wrong though

[DeathAndTaxes]

Check VRM temps.  When load varies like that it could be thermal throttling due to overheating VRM.

A utility like GPU-Z will show you VRM temps.  Note something which only shows a single temp isn't useful.  There are 8 different temps on each graphics card (12 if you have dual GPU card).  The VRM temp (called VDDC in GPU-Z is the one to look at.