In short: specific implementations with POSCAP design are suspected of creating instability specifically with a particularly high boost clock. That results in itself in-game driver crashes and the dreaded CTD (crash to desktop). The solve, reconfigure POSCAPs, add MLCCs.
好似一粒POSCAP=1組MLCC(10粒)
POSCAP cheap過用MLCC
總之應該係兩樣溝埋要有6個
依加好似係6粒用晒POSCAP就會出事
Asus TUF好似係用晒MLCC,我估應該冇事?
:^(
醫護冇護衣
2020-9-26 19:45:07
So, as an Electronics Engineer and PCB Designer I feel I have to react here.
The point that Igor makes about improper power design causing instability is a very plausible one. Especially with first production runs where it indeed could be the case that they did not have the time/equipment/driver etc to do proper design verification.
However, concluding from this that a POSCAP = bad and MLCC = good is waaay to harsh and a conclusion you cannot make.
Both POSCAPS (or any other 'solid polymer caps' and MLCC's have there own characteristics and use cases.
Some (not all) are ('+' = pos, '-' = neg):
MLCC:
+ cheap
+ small
+ high voltage rating in small package
+ high current rating
+ high temperature rating
+ high capacitance in small package
+ good at high frequencies
- prone to cracking
- prone to piezo effect
- bad temperature characteristics
- DC bias (capacitance changes a lot under different voltages)
POSCAP:
- more expensive
- bigger
- lower voltage rating
+ high current rating
+ high temperature rating
- less good at high frequencies
+ mechanically very strong (no MLCC cracking)
+ not prone to piezo effect
+ very stable over temperature
+ no DC bias (capacitance very stable at different voltages)
As you can see, both have there strengths and weaknesses and one is not particularly better or worse then the other. It all depends.
In this case, most of these 3080 and 3090 boards may use the same GPU (with its requirements) but they also have very different power circuits driving the chips on the cards.
Each power solution has its own characteristics and behavior and thus its own requirements in terms of capacitors used.
Thus, you cannot simply say: I want the card with only MLCC's because that is a good design.
It is far more likely they just could/would not have enough time and/or resources to properly verify their designs and thus where not able to do proper adjustments to their initial component choices.
This will very likely work itself out in time. For now, just buy the card that you like and if it fails, simply claim warranty. Let them fix the problem and down draw to many conclusions based on incomplete information and (educated) guess work.
醫護冇護衣
2020-9-26 19:45:23
Edit: it seems EVGA basically confirmed this by saying: " But, due to the time crunch, some of the reviewers were sent a pre-production version with 6 POSCAP’s, we are working with those reviewers directly to replace their boards with production versions.EVGA GeForce RTX 3080 XC3 series with 5 POSCAPs + 10 MLCC solution is matched with the XC3 spec without issues. "
Edit 2: Also, this could be the reason Asus is 'late' whith there cards
Edit 3: it seems Gigabyte uses non-MLCC parts but does not have problems, confirming the point you cant simply judge based on capacitor type and count.
Edit 4: now that JayzTwoCents has done a video about it it all goes wild in that thread as well
1082
2020-9-26 19:46:12
一樣有事
:^(
悠月狐
2020-9-26 19:46:32
:^(
麻瓜青蛙
2020-9-26 19:49:31
In short: specific implementations with POSCAP design are suspected of creating instability specifically with a particularly high boost clock. That results in itself in-game driver crashes and the dreaded CTD (crash to desktop). The solve, reconfigure POSCAPs, add MLCCs.
One AIB has confirmed this:
Hi all,
Recently there has been some discussion about the EVGA GeForce RTX 3080 series. During our mass production QC testing we discovered a full 6 POSCAPs solution cannot pass the real world applications testing. It took almost a week of R&D effort to find the cause and reduce the POSCAPs to 4 and add 20 MLCC caps prior to shipping production boards, this is why the EVGA GeForce RTX 3080 FTW3 series was delayed at launch. There were no 6 POSCAP production EVGA GeForce RTX 3080 FTW3 boards shipped.
But, due to the time crunch, some of the reviewers were sent a pre-production version with 6 POSCAP’s, we are working with those reviewers directly to replace their boards with production versions.
EVGA GeForce RTX 3080 XC3 series with 5 POSCAPs + 10 MLCC solution is matched with the XC3 spec without issues.