Question Extreme 1650 LP overclocking shunt mod? Maximum reasonable power limit target?

[realflow100]

I have successfully shunt modded a pcie slot powered gtx 1650 zotac low profile model card.

Normal card wattage in gpu-z is about 66-68w
So far the highest ive tested is 75w
How much higher would be reasonable for me to try going for? 80w? 90w? 90w would be 15W above the 75w pcie spec

my friend has done a shunt mod on RTX 3090 with about 100-105w power draw through pcie slot!

 

[Gam3r01]

Personally, I wouldnt go any higher than the rated wattage, especially depending on the motherboard in question.
Certain motherboards have 6 pin PCIe ports on them to further support PCIe power draw through the slot, but those are designed for stability, not continuous use.

 

[realflow100]

is there no safe tolerance listed somewhere for like 25-50% above rated or something?
aren't most components usually rated 25 to even 50% above what they will use for reliability and stuff?
it sounds really bad design if pcie slot would die if you used 76w instead of 75w

 

[Karadjgne]

75w is an assumed limit to wattage. It's the limit assumed that a socket, traces, power delivery can handle. Few years ago, the Rx480's were measured at pulling upto 94w from the pcie slot. This was promptly fixed with microcode updates in driver packages and hardcode fixes in later cards limiting them to a 75w limit.

The reasons for this are simple. Every motherboard design is slightly different. Z boards have thicker traces, better or more pure copper, higher rated VRM's etc. B and H boards don't need that because they don't support OC. And that can change per vendor, board, generation etc. So 1 B board might tolerate upto 80w, another B might be 85w and a Z might be 95w, but another vendor might be 5w less for equitable boards. There's No telling exactly.

But all boards will tolerate 75w. (except a few oddball HP etc stuck at 25w limits)

You are trying to make a silk purse from a sow's ear. Not gonna work as intended and if you push it one of two things IS eventually going to happen. 1) destroy the card, 2) destroy the motherboard.

 

[realflow100]

I added a 6-pin connector to the graphics card. which should in theory redirect the the current away from the pcie slot and directly through the 6-pin pcie cable. going straight to the power supply.
here is some pictures.
Would I need to completely isolate the pcie-slot +12v pins to prevent any current being fed through it. Or will electricity just take the path of least resistance. through the 6-pin connector wires I soldered on?

 

[Karadjgne]

Your theory is wrong. If the card pulls 50w from the slot, what you've essentially done is provide a parallel source, so the slot will still provide @ 25w±, as will the cable. You'd need to eliminate the power And ground pins on the card to isolate it from the slot or any circuitry attached to those pins will still be in use.

 

[realflow100]

It would be quite difficult to isolate all the ground pins! I dont think thats even reasonably do-able. theres so many of them.
it would be a chore just to isolate the +12v pins alone.
if the power is shared like you say. as long as it draws less than 75w through the pcie slot.
and draw at least half through the 6-pin connector it should be fine.
With the 15mohm resistor shunt mods it should not draw much more than 90-95w maximum.

 

[realflow100]

I got it to work. it works like I set up. didn't even need to do anything with the pcie slot pins or anything either.
it just "works"
However the ground wires aren't sinking as much current as expected. 1-2 amps and it fluctuates somewhat erratically. kind of concerning.

though the +12v positive wires of the 6-pin do draw the correct current. seen up to 84W or about 7 amps of current draw. MSI Afterburner predicting about 84-90w at the same time.

 

[Karadjgne]

Thermal losses, resistance losses. Power drawn and power returned is never the same, so grounds aren't going to sink as much as the source provides.

 

[realflow100]

So not an issue?
Theres 68 ground pins in the pcie slot! WOW thats way more than the amount of +12v pins. which there was only 5 +12v pins total. before I added the 6 pin connector.

Could be just the shear amount of ground pins available in the pcie slot far outweighs my wires soldered from the 6-pin connector to the grounds on the capacitors.
Or Ive picked sub-optimal location of attaching the grounds to minimize current drawn through the pcie slot.

 

[Karadjgne]

Which are power grounds, which are signal grounds. Audio uses an AC signal on a DC carrier, as does data, basically a data+ and ground situation. You'll have grounds for multiple outputs, not necessarily limited to power.

 

[realflow100]

I dont know what other easy to find/use locations are for soldering the 6-pin to for better ground connection and carrying more current through the 6-pin connector and less through the slot grounds.

 

[Karadjgne]

That's just the thing. The components on the card are built for X amount of power. Things like the VRM's are only rated for so much, and will only draw so much before burnout.

You could hook that thing up every which way, have 1000w capable, it's still only going to pull what it needs. If you try cranking it up past what any 1 single component can handle amperage-wise, voltage-wise or thermally, 'poof', dead card.

That 6pin pcie you added can supply an additional 180w, it's rated for 60w/5A per pin and you have 3x pins.

The card isn't drawing the power. Doesn't matter from where.

 

[realflow100]

I managed to fix it and added even more grounds to the card and even cut off the pcie slot +12v pins from connecting to the board. so its getting only dedicated +12v directly from the 6 pin connector only. and not backfeeding into the motherboard like it was before (causing motherboard lights to blink on for a half a second when shutting pc off)
now it works smoothly and has a whopping +33% higher power limit increase! 90w power limit instead of 66w!