VOGONS


Voodoo 3 Undervolting/Undercloocking

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Reply 20 of 26, by vvbee

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Jackal1983 wrote on 2022-03-03, 04:49:
vvbee wrote on 2022-03-02, 04:30:

With a K6 300 (bottlenecking), I've seen temps reduced by up to 4 C load and idle by downclocking from 143 to 100 MHz, with 0-5% loss in performance up to 800 x 600 (tested in Quake 3, Need for Speed 5, 3DMark 99). So not a big reduction in temps, but also no clear benefit in running the card full blast.

Thanks, that kind of data was what I was curious about. Between that honking huge aluminum heatsink that came attached to the chip and an underclock I should get a decent reduction in temps. Hopefully I'll get a decent temp drop over that mosfet as well.

Probably due to the CPU limiting the GPU, it ran relatively cool even without underclocking, with a case fan bringing in air across the card. Under load, the PCB behind the core peaked at 22 C above ambient, the surface of the MOSFET 16 C, and the surface of one of the VRAM chips 9 C.

This was the Voodoo 3 2000.

Reply 21 of 26, by The Serpent Rider

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Jackal1983 wrote:

And those Vcores are not controlled by the Vbios?

Of course not. VRM was fairly primitive on video cards.

I must be some kind of standard: the anonymous gangbanger of the 21st century.

Reply 22 of 26, by NostalgicAslinger

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Maybe interesting: https://www.youtube.com/watch?v=f0tO6duz_4s

He says, that the stock Voltage of the Voodoo 3 3000 is around 2.6V, and tryed undervolting, still runs stable with 2,25V and 10 degrees cooler.

Reply 23 of 26, by mockingbird

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NostalgicAslinger wrote on 2022-03-03, 17:06:

Maybe interesting: https://www.youtube.com/watch?v=f0tO6duz_4s

He says, that the stock Voltage of the Voodoo 3 3000 is around 2.6V, and tryed undervolting, still runs stable with 2,25V and 10 degrees cooler.

Good find... I wish he would have told us what resistance value he settled on...

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(Decommissioned:)
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Reply 24 of 26, by Jackal1983

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NostalgicAslinger wrote on 2022-03-03, 17:06:

Maybe interesting: https://www.youtube.com/watch?v=f0tO6duz_4s

He says, that the stock Voltage of the Voodoo 3 3000 is around 2.6V, and tryed undervolting, still runs stable with 2,25V and 10 degrees cooler.

That's intriguing. I have a V3 1000 with 6ns sgram (already added a HS and 40mm delta fan to it), it'll be interesting to see what clock speeds that stock lower voltage will support stably. I'll be happy with V3-2000 speeds because I don't think a C3 Nehemiah would be able to take advantage of anything faster.

Reply 25 of 26, by The Serpent Rider

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Jackal1983 wrote:

I don't think a C3 Nehemiah would be able to take advantage of anything faster.

Only if you play in 640x480 mode. 1024x768 and higher, in many cases, will be bottlenecked by Voodoo 3 fillrate.

I must be some kind of standard: the anonymous gangbanger of the 21st century.

Reply 26 of 26, by Jackal1983

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The Serpent Rider wrote on 2022-03-13, 22:22:
Jackal1983 wrote:

I don't think a C3 Nehemiah would be able to take advantage of anything faster.

Only if you play in 640x480 mode. 1024x768 and higher, in many cases, will be bottlenecked by Voodoo 3 fillrate.

Eh, not that big of a deal to me. I have other systems that can pick up the slack, like the Slot A system I'm finishing that has a V3-3500 in it. Besides, the kind of games I'll play on it will be most at home at less than 1024x768 (the monitor I'm going to use with it maxes out at 1366x768 anyhow). I'll try 166 mhz on it but I won't be too aggravated if turns out the chip wants more vcore. I'll be happy with V3-2000 speeds. As long as it's capable of playing Q1, Q2, Unreal, etc at decent framerates (decent to me is 30 fps at most times) I'll be happy.