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pascal TDP limits in bios

post #1 of 4
Thread Starter 
I am seeing lots of posts blaming locked voltages and temps for reasons of performance bottlenecks, when actually the prime reason is TDP limits set low in the bios shipped with the cards.

I think some people assume they can draw 225 watts on a card with one 8pin cable, but the bios is limited to lower limits, in my case 170 watts on my palit, some cards are as low as 140 watts.

There is 2 prime reasons a card can stop clocking higher.

Card hitting TDP limit, so has to throttle to keep power usage in check (on pascal aftermarket this is prime reason).
Card getting close to temp limits, (on pascal this is probably only an issue on FE cards).

The VREL seen in gpuz does mean voltage reliability, and it can mean simply that the voltage is not configured high enough in the bios to be stable so it drops back the speed, however it more likely means that it cannot use the voltage it wants because the voltage would take it over the TDP limit.

Trust me when we get a pascal bios editor, the key to performance will be very simple, bumping TDP limit.

On my old 970, as an example, I seen VREL a lot and it would stop at 1408 clock speed and go no higher on stock bios. It even had instability as well. I initially just boosted the voltages which didnt allow higher performance, it just created more heat and caused more throttling.

Reason is higher vddc = more tdp usage, and if tdp is the bottleneck it wont work.

However when I changed the limit in the 970 bios from 187 watts to 275 watts the card could breathe, higher voltages then actually worked and I went from been constantly at max TDP (until clocked down to circa 1300) to been only limited by voltage/temp.

Why do nvidia cap the TDP? its about performance per watt. As the TDP limit increases the efficiency drops, e.g. going from 187 to 275 on my 970 did not yield a matched % increase in performance. So my performance per watt went down sharply.
Edited by chrcoluk - 7/25/16 at 12:32am
post #2 of 4
This is the exact issue for my GTX1070 SC,as soon as Valley starts i'm seeing 2025mhz after 30sec it drops to 1950mhz and it reaches 1975mhz at most GPU-Z shows that card hits Pwr and VRel.
post #3 of 4
I just got my 1070 SC about a week ago, it seems to cap out around 2100 MHz at stock voltage. I've been running Heaven and GTA V. GPU-Z is reporting perf. cap limits as pwr and vrel as well.

If you haven't already, definitely increase your power target in your overclocking software to it's maximum (113%) and set your priority to temperature. As long as you're stable and your temps are under control, that should give you some extra headroom.

I'm glad someone has an answer to why these cards can't be pushed further, my instinct was that it was being held back, but I didn't know enough to say whether it was my PSU, the single 8-pin connector, or the card's BIOS.
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post #4 of 4
That's kinda simple.
here is the quote from wiki
Quote:
In semiconductor devices, leakage is a quantum phenomenon where mobile charge carriers (electrons or holes) tunnel through an insulating region. Leakage increases exponentially as the thickness of the insulating region decreases.
Simply put, 16nm process has very "thin walls".
So keeping things under control puts some limits on voltage and current that can be used without risking to damage the silicon.
I do think that the limits set by nvidia are very conservative.
there are few ways to to deal with it:
Flash the card with the FTW bios (215w vs 170w), volt mod the card, wait for custom bioses.
BTW, have this 1070 SC card for a couple of month.
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