PNY GTX 780 XLR8 3Gb

Seller Note “Untested”


  • This card has a nice looking design, very clean and still has its warranty sticker. I think I kind of fell for this and judging by the rather obvious issues (not detected, fans run full speed), the seller was not really honest in saying it was untested! Normally I would expect this card has a faulty core, but I will try to analyse it as far as I can as I have never seen a 780 like this and there appears to be little in the way of information.
  • Resistances (low looking Vcore doesn’t look good)
    • Vcore – 2.8 (seems a little low for this type of card, Core is GK110-300-B1)
    • Vmem – 83.6 (good, chip is the commonly used Hynix H5GQ2H24AFR-R0C)
    • PEX – 262
    • 1.8v – Not present
    • 5v – 1.977K
    • 3.3v – 684
    • 12v – $.5K+
  • Voltages (not much in the way of minor voltages, not really what I expected, will dig deeper..)
    • Vcore – 0.05V
    • Vmem – 0v
    • PEX – 0v
    • 5v – 1.2v!
    • 3.3v – Present
    • 12v – Present
  • No direct schematic, the board layout is quite different to other 780s I’ve got or have ever seen.
  • It appears I might have been too hasty (or have a fall coming later), but with the almost complete lack of voltages (only 3.3v and 12v found) and a missing component, there is at least some more analysis to do before confirming the card is dead..
  • Against my initial fears, this card is not only fixed, but seems like an excellent version of the 780! 🙂

Investigating U15 (5v source)

At this stage, I suspect U15 is the source of 5v (guess based on other 780s) and I can see clear issues around this voltage area. The chip is RT7257GLZSP

2 (VIN)High, 12v, 4K+0.86 v! Need to find why this isn’t 12v
3 (SW)1.977K1.19v !
7 (EN)10MOhms?0.01v !

Mystery damaged / missing component!

Well, I don’t know how… but there seems to be a missing component responsible for the absence of the 12v VIN. Considering the card had its warranty stickers and seems in pristine condition, I don’t understand how this happened. I guess it could have just overheated and broken down.

PNY GTX 780 XLR8 – Missing Shottky Diode D6

From other 780 cards, I think the missing component could be a 3A 40v Shottky diode. Before I attempt to replace it, I need to try and understand if there is any obvious reason it seemingly vapourised?

  • Overcurrent through the 5v rail – if so, why?
  • Could the U15 be faulty somehow? Doesn’t seem shorted, VIN has a high resistance and there is about 2K on the 5v output
  • The core resistance still seems a bit low to me, possibly some of the 5v supplied components have an issue? The VRMs seem uniform in terms of ESR, no obvious shorts.
  • A faulty diode?

I will make some comparisons with other GTX 780s I have, in particular EVGA GTX 780 3Gb SC (Card B)

I decided that the variances could be within tolerances, as the PCB layout does see different. So, I desoldered a A34 Shottky diode from the supespected dead EVGA GTX 780 and soldered it on the XLR8 after cleaning the pads.

PNY GTX 780 XLR8 – Replaced Shottkey diode

After checking the diode was working properly (in both directions) and that resistances were normal, I powered on the card and to my delight there was a picture!

Key learnings

  • Initial assumptions can be wrong, always check all the basic readings before jumping to conculsions! I feared this card would end up having a dead core due to not being detected and having it’s fans running at full speed, but it is now very much alive.
  • I didn’t know anything about Shottky Diodes before working on this card. Now I will make sure I check them going forward.

Stress Testing

  • MATS passed 3 tests – good.
  • Komnuster HD, 3D TimeSpy – Passed.
  • Under full load this card seems to be more efficient than the reference GTX 780. It is running a few degrees C cooler and using more power and the GPU core is seemingly clocking higher. I need to do more tests, as I am not sure the proper XLR8 BIOS is on this card. The memory and core clocks show too low in GPU-Z, plus it thinks its the reference when clicking lookup. I might try flashing a listed XLR8 BIOS. It is running at 1032 MHz core and 1502 memory.
  • Subnautic is running nicely at 70 degrees C, better than the reference’s 79/80 degrees C.
  • Overall, it’s the nicest 780 I have! 🙂