Having issues getting refresh rates over 60hz working at 640×480 on a Win9x PC.

[xenphor]

I’m using a Windows 98 pc with a Geforce 4 ti4800se.

Here’s a video of the issue: https://youtu.be/2t6VWe5LUXo

640×480@60hz works fine, as do DOS games at 70hz. However, if I try using refresh rates over 60hz (70, 72, 85) in Windows, the picture will have a ripple (?) effect with “fuzzy” spots throughout, in addition to being cropped. If I change the 384p/400p mode to Line2x 240×360 and mess with the Advance Sampling options for 480p, I can fix most of the cropping issues, but the ripple and fuzzy spots remain.

When using 640×480@75hz for example, the OSSC display shows 500-p 37.50khz 75.00hz. I’m just wondering if there’s anything else that can be done to fix the ripple and fuzzy spots or if the OSSC is not meant to be used above 60hz at 640×480.  If anyone else has used the OSSC with a similar setup I would be interested in your experience.

• This topic was modified 2 years, 10 months ago by xenphor.

[BuckoA51]

What is the display you are using?

Are you able to try the new beta firmware (requires a small hardware modification to OSSC) ? This has fixed several issues people were having with OSSC and retro PCs – https://videogameperfection.com/forums/topic/ossc-v1-xx-series-beta-firmware/

[marqs]

You need to adjust sampling options, especially sampling rate. Start by setting 480p in sampler to VESA more. For 640×480@75, try setting H. samplerate to 840 in advanced settings and adjust H/V backporch to center the picture.

[xenphor]

@BuckoA51 The display is an Alienware 2521HF 240hz Freesync display. I’m not sure I would be able to update the firmware if a hardware mod is necessary since I don’t have the tools at the moment. I could potentially do it in the future if it would improve compatibility for Win9x.

@marqs Alright those settings seemed to help a lot. I took a new video of what it looks like (sorry for poor quality footage): https://youtu.be/eZzWMAKqe9I. I’m still a bit confused by what the 384p/400p Line2x 240×360 setting is doing since according to the OSSC it is outputting 500-p.

Getting 75hz working properly is great. I don’t suppose you (or anyone) would know what 70, 72, or 85hz settings would be? Those are the most common refresh rates for this era of PCs. Thanks for the help.

• This reply was modified 2 years, 10 months ago by xenphor.

[BuckoA51]

Does seem strange that OSSC thinks its 400p… @Marqs any thoughts on that?

[marqs]

I’m not sure why it even reacts to 384p/400p proc setting if your PC is outputting 640×480 (which should fall under 480p/576p group). Perhaps the PSP sampling preset was causing the conflict – that should be only used with PSP source.

[xenphor]

I don’t normally have the PSP sampling option selected. I was just cycling through the different options to show the results since changing from AUTO to VESA helped solve the 70-85hz issue.

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