8087-1 FPU has been added.
No real difference in SimCity observed. Will check later with some other tools.

H3nrik V! wrote on Yesterday, 14:09:

JAKra85 wrote on Yesterday, 12:07:

- Turned on, measured voltages. All good. I got 10,8V instead of 12V and also got a bit sad at this point and less confident about this PSU... too late.
- Tested on a different low value AT board. Measured again, exactly 12.00V (and 4,99V).
- Important: with no load the 12V measures way less that 12V!

I would fear that the lower unloaded voltage could be a symptom of some regulator not working correctly - maybe from dried up capacitors?

I might have used a wrong phrase or wording here.
Unloaded not equal to powered on and idle state.

In this case I used "unloaded" as not connected to anything. With PSU powered on and AT pins P8 and P9 hanging in the air and measured voltage.
Upon further investigation this is natural as many classic power supplies require a load on the 5V or 12V rail to properly regulate and output correct voltages.

"- Tested on a different low value AT board. Measured again, exactly 12.00V (and 4,99V)."
Measured this by connecting to an AT motherboard, powered on and low load.

JAKra85 wrote on Yesterday, 14:50:

8087-1 FPU has been added.
No real difference in SimCity observed. Will check later with some other tools.

SImCity uses the FPU in specific circumstances, you wouldn't really see a benefit in moving around a map

https://michaeldale.com.au/archive/2026/06/07 … y-use-your-fpu/

(The usage is the same for original and 2000)

NeoG_ wrote on Today, 04:53:

SImCity uses the FPU in specific circumstances, you wouldn't really see a benefit in moving around a map […]
Show full quote

JAKra85 wrote on Yesterday, 14:50:

8087-1 FPU has been added.
No real difference in SimCity observed. Will check later with some other tools.

SImCity uses the FPU in specific circumstances, you wouldn't really see a benefit in moving around a map

https://michaeldale.com.au/archive/2026/06/07 … y-use-your-fpu/

(The usage is the same for original and 2000)

Good read!
I can confirm, not many games used FPU before Quake engine and even those that used it have no breathtaking uplift.

Google AI was misleading with up-to 50% increase... when asking for 8087 FPU upgrade. 😀
Pointed to a Reddit post with SimCity Classic with FPU +50% uplift, that Reddit post pointed to this Vogos entry:
Interesting findings with simcity classic
Yeah, but here it's a 386 with 387 FPU, not really comparable with 8088 with 8087 FPU.

I will do a bit more test and research.

I've read previously that the FPU can become hot, but damn... it's like dangerously hot. Thinking adding some heat sink...
I specifically choose 8087-1 with 10MHz, thinking that if the FPU is rated to 10MHz when running at 4,77MHz it will be cooler than the one rated to 5MHz.

Software written using QB 4.5 does use a math co-processor, if available.

Examples:
https://www.youtube.com/watch?v=mYJ1IPph4tw
https://www.youtube.com/watch?v=FaQa9INqZf8

Edit: This might be of relevance in so far, because QBasic/QB had quite a community in 90s and early 2000s.
Many applications and games had been written using them, many websites had offered QB 4.5 examples and tutorials.
So depending on the situation, the QB runtime can make use of the x87 math co-pro.

Very cool system! 😀