maybe capacitor replacing might help, creative used cheap capacitors on them and they didn't age well, and also maybe put blanking plates on the PC to block radio interference.

Specs of the rest of the system?

cyclone3d wrote:

Specs of the rest of the system?

Pentium 100
Startech 300W ATX Power Supply
Intel TC430HX
64 MB RAM
Cirrus Logic GD5446

Do you have the PC Speaker connected to the SB? If you mute the internal speaker input with the W95 mixer does the noise go away?

JudgeMonroe wrote:

Do you have the PC Speaker connected to the SB? If you mute the internal speaker input with the W95 mixer does the noise go away?

no, i don't have the pc speaker connected to the sound card, i have the PC case speaker connected to the PC speaker port on the motherboard.

Check power supply of the computer. Check 7809 stabilizer IC on the SB card.

georgel wrote:

Check power supply of the computer. Check 7805 stabilizer IC on the SB card.

that power supply is fairly new, i just got it a few months ago. I later put in my Sound Blaster 16 CT1740 and i don't hear any interference unlike the SB Pro 2.0, i also put on blanking plates to hopefully eliminate RF noise. I later put the SB Pro 2.0 in my ASUS VX97 full tower P133 build and I don't hear any RF noise or whining unlike the other machine. It's also on top of the table unlike the P100 PC that is on the floor next to my main Windows 10 PC.

You know, I have kind of the opposite problem... the card has that annoying "thinking noise"/whine when idling in DOS command prompt, but it goes away when playing DOS games or in Windows 3.1. I have that same problem both of my SBPro 2 cards, tried different (good) power supplies, as well as several motherboards to no avail. Strange thing is that even my SB 2.0 produces less background noise, and also like you the 1740 does not whine at all.

I guess it may have to do with how well the motherboard filters out noise in the ISA bus.

TheMobRules wrote:

You know, I have kind of the opposite problem... the card has that annoying "thinking noise"/whine when idling in DOS command prompt, but it goes away when playing DOS games or in Windows 3.1. I have that same problem both of my SBPro 2 cards, tried different (good) power supplies, as well as several motherboards to no avail. Strange thing is that even my SB 2.0 produces less background noise, and also like you the 1740 does not whine at all.

I guess it may have to do with how well the motherboard filters out noise in the ISA bus.

my main Windows 10 PC even has that annoying thinking noise/RF interference on the onboard sound card, it's worse when i use headphones.

Check the circuit around the 7809 IC.

georgel wrote:

Check the circuit around the 7809 IC.

looks ok

Look with oscilloscope!

Try a different video card or move it to a different slot.

The SB Pro 2 (and all earlier Creative cards) is known to pick up any interference, this was even back then. It's not an issue with it aging. It's just badly designed.

Startech 300W ATX Power Supply

Does it have a -5V rail? SB Pro 2.0 needs -5V, that may be you rissue.

derSammler wrote:

Try a different video card or move it to a different slot.

The SB Pro 2 (and all earlier Creative cards) is known to pick up any interference, this was even back then. It's not an issue with it aging. It's just badly designed.

Indeed. I had new SB 2.0 back in the 90s and I could hear bytes chirping in the data bus of my 286 at all times 😉 - it's the same case with every CL card in my collection from similar Era (CT1600 and early, less integrated SB16s)... it was way into 90s when CL started making cards featuring better integration and significantly less noise.

My CT2290 also picks up ISA bus interference in the form of hisses and clicks on 286-386-486 motherboards. It's just the way Creative Labs junk rolls.

appiah4 wrote:

Startech 300W ATX Power Supply

Does it have a -5V rail? SB Pro 2.0 needs -5V, that may be you rissue.

the PSU has a -5v rail, thats why i bought it from amazon a few months ago.

appiah4 wrote:

My CT2290 also picks up ISA bus interference in the form of hisses and clicks on 286-386-486 motherboards. It's just the way Creative Labs junk rolls.

The real problem is that the motherboards should have good filtering designed into them. So it wasn't just Creative's problem.

Get a board that doesn't have electrolytic caps or doesn't have filtering caps on the ISA/PCI/whatever bus and you will have noise.

Can a motherboard be modded to be less noisy ? If so, what needs to be done ?