Same issue, it goes from 60 to 59 very quickly then drops to 30... wierd.
The slight fluctuations in the average FPS are to be expected. The large drop to 30 is a biproduct of how vsync works. If your card can't keep up it no longer has the option to draw at 55 frames per second, a 60Hz refresh rate means that it will drop down to 30fps.
RefreshRate/NumberOfIntervalsToRender = frames per second
Which provides you with a discreet set of values
presuming a 60Hz refresh rate that's 60, 30, 20
60/1 = 60
60/2 = 30
60/3 = 20
and so on
thats exactly what i see (have to look really carefull though its really hard to spot on most settings but it really jumps down to 21 even really shortly once per 1-2 secs you can see it.)
with vsynch on and max fps foreground set to:
at 66 i get 60 most the time but incredibly fast fluctuating 64-60-59, 32 , and even 21
(69% gpu load, mem controller 36/37 load, cpu load goes bananas though -11,32,20,43,34,30,25,38,05,43,27 (thats D3 alone not total cpu use) toon standing still in game.
at 60 i get 32
at 33 i get 32 (but really steady) gpu load 37%, mem.contr.20%, cpu load 0-5%, and 10-20C cooler vidcard.
at 32 i get 21-32 fast wobble
i find the 'if the card cant handle it you get 32' really wierd though.. the card can run 80-130fps if i 'let it go full throttle' its just silly how fast it heats up then though
its really inconsistant too.. i've been fiddling with nividia driver settings last night and at one point i had a pretty steady 60fps , still a bit of wobble but ALOT less..
now i log on again this afternoon its back to fast wobblefest.
indeed slight variations i would consider verry normal.. but in D3 it just goes completely mad.
guess the latest nvidia driver of may 22th doesnt help any at all on this? I can save me the trouble of updating then :)
so far only 33 set is the setting that works 99% of the time ( it was 32 the first 2 days diablo came out but now that one wobbles fast between 21 and 32) and is super steady compared to the others.
since the game has virtually no cpu use at that setting my guess is the game or driver has trouble allocating a steady cpu load , or buffers dont work well. (sounds wierd but check the load on your cpu) - again it can be a bit more steady one day and alot more jumping in slightly different range the other day
turning vsynch off in game has no effect at all on the numbers either btw (driver profile set to appl. controlled) - [windowed full screen gives me stutters]
core2 duo E8400, geforce 9800gtx+ , driver 285.58, win xp pro (32bit) - full screen mode, 1920x1080
just tried out different screen resolutions and windowed/full screen.. get back to my good old 1920x1080 full screen turned vsynch off suddenly its steady at 60 (no drops to 32/21) but if i set the slider on 60 it is 32 fps :P how silly is that? vsynch is off? meh now its 64-32 wobble again.. but do get tearing so vsynch is off imo.
just cant trust any of these settings 100%
alt tab, or restart of the game and its different again.