[I’m not sure if this should become a new thread. Opinions welcome!]
OK, so I bought another Dell micro-PC, this time an 8th-gen version with an i7. I wasn’t sure if the i7 with multithreading was better than an i5 without, but the (retired) engineer in me was curious. And the refurb that I found was cheaper than some i5 offerings. So, I set out to test a) G7 Kaby Lake vs. G8 Coffee Lake CPUs; and b) whether multithreading helps a Cantabile PC. 2.8GHz veteran vs 2.1GHz youth, so to speak. Except, it turned out to be way different than I expected …
Both PCs have 32GB of RAM, and use 12GB for a RAM drive to load samples and VSTs. Both are running ‘headless’ using Remote Desktop for video/kb/mouse, and rtpMIDI to pass MIDI data back and forth. They aren’t identically set up, but close, particularly when driven with prerecorded MIDI from a DAW.
I tested a set of 4 songs that I ended up having to simplify a little in my current setup, because my i5 would glitch now and then. Would the original versions work on the new machine? Nope. In fact, they were worse – a lot worse in some cases! I started looking for configuration mistakes, or some unneeded app that was hogging the CPU. That’s when it dawned on me: my ‘i5-7600T’ is really an i5-7600: 65W (vs 35W) TDP, 3.5GHz (vs. 2.8GHz) clock. There was a note in the ad saying that, “We may substitute items of greater value in some circumstances.” So, I paid for an OptiPlex 5050 with an i5-7600T, and got an OptiPlex 5070 with an i5-7600.
So, how does a slower, cooler 8th-gen T-class i7 processor made for laptops stack up against a midrange 7th-gen i5? Not so well, I’m afraid. The i7 has twice the L3 cache and 11% faster RAM, but it still runs at 2.1GHz, and has problems running songs that have evolved into ‘typical’ for my rig. The Cantabile Time Load was particularly disappointing, running near-100% in the best case, and well over 300% in some songs. Surprisingly, the reported CPU load was low – 20-30%, on average – but the audible results were glitchy. I wasn’t able to get things to settle down without resorting to 20-25 mSec of latency in the ASIO drivers. Since both CPUs are locked, I can’t play with either clock to try to level the field.
So, for a system filled with VA synths like mine, it seems that CPU (FPU?) speed is the dominant factor. I tried using the new system for sampled guitar, but even there complicated patches were showing weakness. The setup worked – as long as I didn’t change anything mid-song.
I’ve ordered an i5-8600 with 6 cores and a 3.1GHz clock to upgrade the i7; we’ll see how that fares. At that point, the test will be 6 cores at 3.1GHz vs 4 cores at 3.5GHz. The 8th-gen CPU should win, unless it runs hot enough to start throttling.