eGPU Activity Led Modding

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Avexrion

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Jul 23, 2015
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Wasn't completely sure where to post this, but as this mainly involves a GPU, this seemed the most appropriate.

I am building an eGPU with a PE4C V3.0, a Fractal Design Node case, and a GTX 770. As odd as this seems, I also want to somehow hook up the case Power and HDD activity LEDs as well.

The power seems fairly simple as I can hook it into the ATX PSU's 5v line (possibly with a resistor to lower the voltage.) However, I am also curious if there is a place I can hook the activity LED (so I can see either GPU activity/intensity, or total power usage.)

Do the GTX 770s have some sort of either "voltage range output" (from 0-3.3v) that shows usage intensity, or a HDD "on off" method which blinks faster when it is used more on the card by chance?

If that does not work, I can also imagine hooking the led to the same line inside of the PSU that goes to the fan (provided it does not use PWM to increase/decrease speed.) This would show power usage at least.
 
I've seen this done before in hardware, the old BeBox units had dual LEDs running down the case that showed CPU load. Usually, there are not specific hardware hooks (a analog voltage output corresponding to load or demand, etc), so I don't think you'll get quite so lucky on a modern GPU (unless you are looking at something like fan voltage, which will correlate, but not be an exact representation)

Your best bet may be to use a bit of software glue - read the values you want from software, and then use a USB driver and a bit of hardware glue to interface to your LED arrangement.
 
The fan header is certainly a possibility, although it is likely PWM and 12v at this point. Some smaller fans do use 5v though, so I will need to look into this.

I'd rather stick away from having to use software. The less "hooks and bits" from the computer's OS, the better.

The only other idea I can come up with might be actually modding the PSU and attaching one 2 pin header to the 3.3v line (so it turns on when the PSU is on,) and one to some sort of mythical PSU "power load" connector within it (aside from the fan, which is probably PWM as well.)

The PSU used is specifically a SS-600ET.
 
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Nope.

Nothing like this exists in modern GPU's.

"and one to some sort of mythical PSU "power load" connector within it"

There is none.

Your only bet is to throw a shunt resistor in across the 12v line, and read the value with an ammeter/voltmeter - the 50v DC meters that hit up to 50A on ebay go for around 10$. It will show you V and I in real time, so wattage is easily obtained.

I use them all the time in my audio projects to make sure the PSU isn't being overloaded - should work fine for a PC PSU too.

Though, remember, the Motherboard supplies up to 10a on the GPU - so you may not be as lucky.
 
I was also thinking about something like that as well, just wasn't quite sure how to do it or if there might be voltage "droop" over time which would affect the readings. I'll read into the shunt resistor idea then and see if that is viable.

If nothing else, I'll just stick to the power led only. That's simple enough, just need to find a 4 pin molex to 2 pin LED header (or see if I can engineer one myself.)

Thanks for the responses.
 
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