HD7950 Core Clock Fluctuating

[Confused]

Hi all,

Playing a little bit with my XFX 7950 today, and have an interesting thing happening...


I've so far got it to 1300/1700, and I've managed to unlock the voltages (using the /xcl command line flag on Afterburner, was previously using Trixx) and have it set to 1.25v, which, with vdroop, is going down to around 1.16v under heavy load. (Before doing so, it was not going above 1.15v at all, and I couldn't push the core above 1200 without 3DMark crashing)

I've now noticed that the core frequency is fluctuating whilst benchmarks such as Fire Strike are running. GPU usage stays at 100% during these times, and my i5-3570 (@ 4.6GHz, upped today from 4.1GHz!) is running at around 40-60% utilisation.

Temps are good - GPU core at around 45C, VRMs at around 60C (watercooled, with an EK full-cover block)

Am I simply pushing the GPU core too hard, and causing it to throttle back?

 

[Confused]

Ahhh...

When I moved from Trixx to Afterburner, the Power Limit changed from +20 to 0, and I forgot to set it to +20 again!

I've set this now... and the fluctuation has gone!

 

[Confused]

I spoke too soon

Still have fluctuations of core clock at 1300MHz, but none at 1200MHz.

Have I reached the limit of my card at the voltage I can supply it?

Even with the limits increased in Afterburner, I can ask for the full 1.3v to be supplied to it (can I get this to go higher?), but under load it's dropping down to ~1.18v - and with it, the core clock drops and performance suffers.

My ASIC quality is 79.6% according to GPU-Z