I've recently done some RightMark measurements on my Onkyo SE-200PCI sound card (external loopback using nice Blue Jeans cable), and I'm seeing some noise and distortion spikes and artifacts that I otherwise have not seen in other RightMark, external loopback measurements I've seen for the card. I've touched on this in a couple other threads, but now I'm asking outright: How can I maximize my sound card's performance (reworded: What is causing my measurement "issues")?
So far, I've seen a few recommendations. Some I've tried, some I haven't had a chance to, and some I'm trying to find more info on:
1. Better RCA cable - Done. This had a noticeable impact by dropping any 60Hz noise and distortion spikes by roughly 5-6dB.
2. Better PSU - I've been looking at PSU's that test really well, such as the Corsair HX850. This one in particular had very low ripple. I do need a beefy PSU, given that I'm running a gaming rig. I'm currently using an Antec EarthWatts Green 650W. I'll need to upgrade down the road for SLI anyway, but I'm wondering how much of a difference I'd see by changing PSUs.
3. Better motherboard - Currently running a Biostar TZ77XE3, and I have no idea how capable it is when it comes to noise and electrical filtering. In fact, I'm having trouble finding good information on this at all. What motherboards have good filtering and power distribution? Which don't? How much does this realistically affect a dedicated sound card like I have?
4. Grounding the card- My measurement artifacts could be indicative of grounding problems, either at the sound card, motherboard, or PSU level. I believe I currently have paper washers in between the screw, sound card bracket, and the case slot opening. So, when screwing the card into the case, I have: Screw -> paper washer -> sound card bracket -> paper washer -> case/slot. I did this because they came with my previous card, but I'm wondering if this might be causing grounding problems. I know some cards rely on grounding to the case, some to the motherboard, and some can do both. I know some previous Auzentech cards would buzz unless you isolated the card bracket from the case (wrap in electrical tape or something). This is something I'll have to experiment with.
5. Grounding the motherboard - I can't remember, but I might have paper washers under the motherboard mounting screws. I've read some claims that this can cause grounding issues with the case. That's another thing I'll have to experiment with.
Any thoughts or suggestions on these? Anything else I should try or am missing (ex: motherboard settings, card layout, etc.)? I am seeing some measurement artifacts from my vintage receiver's HPO, and I figured it would be good to start by making sure my sound card is working properly given the artifacts it exhibited. It could also be performing just fine, and perhaps the artifacts only show up in a loopback test on my system and not actually being output when used regularly.
In case it helps, my system is as follows:
Intel 2500K OCed to 4.5GHz at ~1.35V - True Spirit 140 cooler
Biostar TZ77XE3 Motherboard
8GB DDR3 Ram - 1600 - Forgot the exact type
MSI GTX 780 Gaming - Outputs to 27" 1440p IPS monitor, OCed to 120Hz
Onkyo SE-200PCI sound card
Antec EarthWatts 650W GREEN
Fractal Design Define R4 Case (no window)
Asus DVD burner
4 140mm fans (2 in front, 1 bottom, 1 back)
2 UV Cathode lights in front of case (comes as a kit with a small adapter)
