Stable 12V is the important part, If in doubt hook up a couple more old IDE or scsi drives for more load and recheck the +12v, if it is still ~11.7 to 11.8v it is fine.
In 1998 the Intel ATX spec called for: "Table 3: DC Output Voltage Regulation:
Output - Range - Min. - Nom. - Max.
+12VDC* ±5% +11.40 +12.00 +12.60
* At +12 V peak loading, regulation at the +12VDC output can go to ±10%."

Voltage on my multimeter varied between 11.69 and 11.73 volts. The lower voltage was when something happened, ie when system post was going on, when switching from 2D to 3D with 3Dmark. But recovered soon.

I'll test again some time and attach some extra drivers to see what happens.

If you find that it is stable under increased load, then it might just need adjustment. Some PSUs have adjustment pots inside.
I've never adjusted one, but it might be better to only move it with the power off or with some truly garbage hardware since you don't know how smoothly it will react to the pot.

Ripple is also a consideration .

https://www.eevblog.com/forum/projects/how-mu … su-is-too-much/

I could look if there are some pods present if the voltages will drop to much with more load. Just hooking upa few more hard disks will do the trick 😀

About the ripple: I don't have anything pointing that way as I didn't notice any instability. It ran fine through the tests. Also I don't have the equipment to test it.

The Aopen fsp235 PSU specs mains max as 3.3v @ 14A, 5v @ 22A, 12v+@ 8A (for 96w on 12v) from what I can find. So yes adding 2 more old HD's that draw 1A each on the 12v each plus your current board and stuff should load the PSU to near 5A or more or 60w+ on the 12v which would be mid power point and a good place to check it. I keep a couple old HP big scsi HD's with bad sectors around for these type tests. Many of the IDE draw only .5A on the 12v but read the labels as they should tell you.