FurMark or GPU-Z, which one to trust?

I'm having this small problem while running benchmarks on my Sapphire 7870 in FurMark. For the sake of making sure that this is not an issue due to overclocking, I have my GPU set to stock GHz Edition clocks and AMD Overdrive is off. What is happening is that during the 15 minute benchmark in FurMark, the "GPU Load" meter very occasionally drops down to 64% from 99%, and then quickly goes back to 99% again. The number that it drops to is always 64%, and it only happens maybe between 3-4 times per 15 minute burn in, and only for a second or two each time.

However, while analyzing the GPU-Z logs I had running during these benchmarks, it does not show any drop down to 64% of load, the only drops it shows are the occasional 1-2% or so, which I assume is normal. So my problem is I'm not sure which program has the more reliable GPU load monitor. If GPU-Z is correct, everything should be fine and I can proceed to not worry about this. If FurMark is correct though, I obviously have some sort of problem with my GPU or software.

What do you guys think? Which program is correct here?