Meaning of the JP1 5v SB5V Jumper on a PCChips Socket 7 mainboard? \ VOGONS

Meaning of the JP1 5v SB5V Jumper on a PCChips Socket 7 mainboard?

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First post, by Marentis

Posted on 2020-07-08, 10:49

Marentis Offline

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Hello guys,

does anyone of you know what the jumper with the description "JP1 5v SB5V" on a PC chips 599lmr does?
I have the manual here but it doesn't say anything about that jumper and googling for sb5v gives a
hint that it might be related to the RAMs voltage selection but from what I know SDRAM never
came in a 5v variant but always required 3.3v. Other sites are arguing that it's about the stand by
voltage for usb (hence the SB) but that wouldn't explain that description.
The mainboard also only supports SDRAM, no EDO RAM so does anyone have an idea what this jumper
might do?
Is it maybe just a left over from other mainboards from PC chips with EDO ram support?

Reply 1 of 4, by dionb

Posted on 2020-07-08, 12:48

dionb Offline

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Sure it's JP1?

Looking a this manual it's JP20, and it says this:

Jumper JP20: LAN Power Selector This jumper selects the operating power of the onboard networkadapter. Leave this jumper at the […]
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Jumper JP20: LAN Power Selector
This jumper selects the operating power of the onboard networkadapter. Leave this jumper at the default value 5 Volts.Function
Jumper Setting
5 Volts Short Pins 1-2
SB 5 VoltsShort Pins 2-3

If it's this jumper, it's for the LAN, whether it's powered by regular 5V (so completely dead when ATX power is off) or VSB 5V (so it is still powered when ATX is powered off, allowing Wake-on-LAN, but eating current continuously as extra expense).

Reply 2 of 4, by Marentis

Posted on 2020-07-08, 13:29

Marentis Offline

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Yes, it is undocumented and clearly marked as "JP1 5v SB5V".
I can't find any reference to it in the manual.

Reply 3 of 4, by kalohimal

Posted on 2020-07-08, 13:39

kalohimal Offline

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Looks like the 5V standby voltage to the keyboard or USB, for "keyboard power up" or "USB power up". If the jumper is 5V, it takes power from the 5V rail of the PSU. If it is SB5V, it takes it from the 5VSB line, which is on all the time, so that the keyboard/USB device can wake up the PC. Usually the default is 5V.

Slow down your CPU with CPUSPD for DOS retro gaming.

Reply 4 of 4, by Marentis

Posted on 2020-07-08, 14:40

Marentis Offline

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Aaaah, thank you very much! 😀 The things you learn everyday.

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