4770k, asio spikes with hyperthreading off

hi folks,

just set up a new rig, asus z87-plus, i7 4770k, 16gb ddr3 1600. disabled speedstep, c-states etc. cubase 6.07.

with hyperthreading ON, playback of a heavy-sh project is fine (around 65% on asio meter). with hyperthreading OFF i get alot of asio spikes. frustrating as i can see the asio load in general is quite a bit lower other than the spikes. isn’t it supposed to be the other way round - asio spikes sometimes with hyperthreading ON, then they go away when you turn it off? i’m comparing loads on this particular project at 512 buffers. with hyperthreading OFF, the spikes dissapear as soon as i switch to 1024 buffers.

any ideas?

There are a number of writings about HT/Cubase and it appears that this used to be an issue, but not so much anymore. I am not stating a fact here, but a conclusion based on various posts, etc. With Cubase having the ability to spread over multiple cores and the same with HALion (as two examples), it would seem logical that more cores would be beneficial, if these settings are turned on.

I do have a computer with a Sabertooth Z87, 4770K, 2x 8 GB RAM (so 16 total and one snap higher frequency) and SSD’s instead of hard drives. HT is not disabled.

BIOS power save options are disabled, Windows “Power Options” = “High Performance” and advanced power “save” settings disabled, Windows Search service disabled, The Performance Options are set as follows, Visual Effects tab = “Let Windows…” (not really sure about this one, tried “best performance” and saw no apparent difference) and Advanced tab = “Programs”. I may have forgotten something that I changed, will add if I remember anything.