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  #11  
Old 01-30-2018
Rasmus0909 Rasmus0909 is offline
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Also, is 300W through an 8 pin connector unreasonable?
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  #12  
Old 01-30-2018
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Quote:
Originally Posted by -The_Mask- View Post
Probably depends on the stuff your using. But you should be careful with that, you don't want it leaking in your PSU if it's highly conductive.
All the more reason to use silicone oil (an insulator), but only the very slightest amount is needed. Use the stuff with a solvent, but make sure no acetone is included (dissolves a lot of plastics).

Last edited by ashiekh; 01-30-2018 at 07:04 PM.
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Old 01-30-2018
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Quote:
Originally Posted by Rasmus0909 View Post
Also, this video is stating the total opposite. Could you maybe find some literature that supports your statement?
The video is right, but there is a quantum tunneling effect going on for small gaps; so yes, it does seem strange to be using an insulator.


http://www.w8ji.com/dielectric_greas...ive_grease.htm
"In regular low voltage multiple-pin circuit connectors, such as automotive applications, flooding with a proper insulating grease of low-viscosity dielectric grease is perfectly acceptable unless a manufacturer recommends against it."

I prefer oil over grease in computers as I want a hardly noticeable film, not stuff that can get everywhere and that might lead to a thick film between contacts.

The reason I use silicone oil is that it does not attack carbon based plastics.

Bulb grease
https://www.amazon.com/Light-Bulb-El...ds=Bulb+Grease
it better not be conducting as the example shows mains voltages involved; mineral oil is being used in this case.
"The Electralube lubricant is a nonflammable, non-toxic food grade specially formulated mineral oil that is rendered during a specialized distilling process, creating the perfect consistency to lubricate electrical connections to protect and prevent corrosion."

Here is what is written on the back of my tube of Permatex Dielectric Tune-up grease, a 12V application
"
Connectors and Battery Terminals
...
3. Coat both parts of terminal contact with Dielectric Grease
"
The other application is for spark plug boots (as per the video), and it works great in both applications. I cover the base of my car bulbs in this, and they work well, satisfying the contradictory requirements of conducting at the terminals but not shorting anything out.


Silicone oil/grease has worked wonders for me, but

Normal disclaimer: Use at your own risk; I cannot be held responsible for what you do

I felt I should mention avoiding using silicone oil in high current switches.

All said and done, those contacts should have been fine by themselves and not need such assistance as is being suggested here.

But I do NOT use silicone oil for computer fans, there I feel a need for a real lubricant and use fully synthetic motor oil.
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Last edited by ashiekh; 01-31-2018 at 03:17 PM.
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  #14  
Old 01-30-2018
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DSCF2078.jpg dmOn2.jpg

Hard to see from the small review photo what kind of Grfx cables you get or got, it looks like you get some cables with double connectors, as in a cable that has dual heads, a jumper connector, see photo two

If say, you had the jumper / pigtail cable plugged in, they say here that the pins can burn up, too many amps through the cable, which is why you don't want to use the jumper cable type, instead you run discrete cables to your card

225watt_Limit.jpg
foo-ey on those jumper types, a burnout's what you're s'posed to get on high-draw cards

As for whether a jumper type is rated for 300watts (where each 8pin or 6+2 is rated at 150watts each per ATX standard, ergo 150 x 2 = 300w), I don't treat mine like they are; this article tries to say a jumper type is rated for 300w, merely by virtue that it has x2 8pins on it, but again, that 300watts has to go through the primary 8pin wiring 1st, as it sends 150watts over to & through the parasitic jumper, so, maybe someone can clear that up (under those conditions, it seems a single 8pin cable itself should carry a 300watt rating, which is why I do not trust that jumper types are rated for 300w, once u think it through > I wouldn't want 300w coming out of the PSU pins, would be my complaint): The Math Behind GPU Power Consumption And PSUs > AWG: Cables Everywhere! > section: What Could Go Wrong? > "Let’s take a look at a cable with two eight-pin leads, which should be able to carry 300W (2 x 150W), according to the ATX spec"

big_radeon-hd-5970s_jpg.jpg
As a for instance, I'd never use jumpers on a high-draw card like the 300w 5970s seen above; I'd bust out x4 cables & lay the jumpers to the side, in order to load-share / balance ... so, if you have at least x4 Grfx ports on the PSU panel, are you using x4 discrete cables? Or did you deploy x2 cables that have jumpers, and those melted a little? What's your setup relative to the Seasonic chart & cable pics? I have read that burnouts can be attributed to a poor connexion, say, one of the pins is backed out inside the connector > inspect pins 1st, & to test, tug on each wire, see if the pin backs out (or plug it in then pull it out, inspect pins are still stable / secure / flush inside connector) ... I think I'd inspect the pins also at both ends of cables, make sure they're all formed as tight squares, as opposed to say one of them is ballooned out and not making for a nice tight fit (if so, compress it back into a square)
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Last edited by Cass-Olé; 01-31-2018 at 04:55 AM.
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  #15  
Old 01-30-2018
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Quote:
Originally Posted by ashiekh View Post
The video is right, but there is a quantum tunneling effect going on for small gaps; so yes, it does seem strange to be using an insulator.
Could you elaborate more on the quantum tunneling? A dielectric is naturally an insulator, and it is technically true from quantum tunneling that any particle with wavelike properties can tunnel through a regularly insurmountable barrier. Technically, since humans have wavelike properties (but out wavelengths are so very small) I can run into a wall and tunnel through the wall. But the chances of it happening are like 1/1^1000000^1000000^1000000etc.

Electrons do have smaller mass and therefore have larger DeBroglie wavelengths, but tunneling is still not common and is always based on mathematical probability.

I watched half the video and it shows that the grease is used to prevent arcing. How does electron tunneling help his case of melting connectors? What will the grease actually do to help?
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Old 01-30-2018
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Originally Posted by turkey3_scratch View Post
Could you elaborate more on the quantum tunneling?
The barrier is very thin and the voltage relatively high, so the probability is near 100%. Flash memory is based on quantum tunneling of electrons; a tunnel diode is another. So actually quantum tunneling is VERY common (we won't get into how it helps nuclear fusion in the Sun). Quantum mechanics is fundamental to the operation of transistors, so that covers the computer and its power supply.

But let us just pretend we don't know this; classically it takes about 1000V to jump a 1mm air gap, so if the gap is around a micron, and it will actually be MUCH less, then even a fraction of a volt could jump it. Quantum mechanics just makes it even easier.

The video explains how a thick grease coating insulates against arcing (and most of that is probably just keeping moisture out), but in the case of connectors the oil thickness is very small; the oil is just helping to keep the contacts from oxidizing without obstructing electrical conductivity.


One could imagine all sorts of secondary benefits such as the oiled contacts smooth with wear and so the contact area increases; or that the oiled surface can more easily clear itself of any oxide.

Last edited by ashiekh; 01-31-2018 at 03:08 PM.
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  #17  
Old 01-31-2018
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Quote:
Originally Posted by Rasmus0909 View Post
Also, is 300W through an 8 pin connector unreasonable?
Yes TBH. Seen those burned at power draws in that ballpark.
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Old 01-31-2018
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Originally Posted by rafal_iB_PL View Post
Yes TBH. Seen those burned at power draws in that ballpark.
Mueller's Upgrading and Repairing PCs book claims a PCI Express 8-pin connector is good for 150W; if so 300W would be an issue.

There are only three 12V lines in a PCI Express 8-pin connector, four in an 8-pin power connector

Last edited by ashiekh; 01-31-2018 at 11:33 PM.
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  #19  
Old 02-01-2018
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Quote:
Originally Posted by ashiekh View Post
PCI 8-pin is good for 150W; if so 300W would be an issue
Capture1.JPG
I posted a link to the Tom's Guide article which is a thorough look into the ultra-hi-power Radeon 295x2 & what it will take to otherwise safely run one. There are qualifying words about 'jumper' 8pin cables (photo) like 'should' & 'suggest' a 300w capability simply because it has two connector heads on it ... the problem is, if you remove the jumper, & it becomes a single 8pin, that one head reduces to a 150w rating. Because these jumper heads are wired in series, it does not follow, at least to me, that the cable magically becomes rated for twice the power, for in effect if you wired three heads on there, the cable wouldn't carry a 450w rating, so why would two carry a 300w rating

No one's yet called the Toms article into question, however the Seasonic chart says to limit power consumption when using jumper 8pin cables to 225w ... but then again, 75w should come through the PCI-Express slot, this leaving 150w through the PCI cable (75+150=225w). If Tom;s is right (300w), the cable should be able to be approved for say TitanZ (375w card --> 150 8pin +150 8pin + 75 PCI-E slot), from there, the disparity between 225w cards and 375w cards is just too great

Whether a jumper cable is rated for 150 or 300, I don't care personally since I refuse to use that type anyways, & advise the use of two discrete cables simply because they're better. The original poster has yet to say if his pins melted inside of a jumper-type cable (why would pins melt inside discrete cable pairs on such low power cards --> they wouldn't), so does anyone have info at what point (how many watts / amps) the jumper-types are reliably scheduled to melt?

Per Seasonic chart that advises a 225w card max use, does that mean 225w through the cable or is that 150w + 75w through PCI-Express slot ... in other words, 225w though the jumper implies a 300w card (225 + 75) or at least use to (in the old days, we factored in upto 75w through the slot, maybe some cards are different now as the Tom's article suggests)

Molex offers standard 9amp pins and premium 13amp pins, so use scenarios for jumper-types should differ in their max amps / watts, depending what's being used, therefore the cables should differ in their recommended capacity etc, so what is it, what are the numbers, no better place to ask than here --> Dual-8pin cable in the photo doesn't 'suggest' a 300watt rating to me, happy to hear different
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  #20  
Old 02-02-2018
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It doesn't magically become capable of 300W and this is why daisy-chained PCI-E connectors are not good. KCL is still a thing.

Quote:
the Seasonic chart says to limit power consumption when using jumper 8pin cables to 225w
This is more reasonable from what I can tell. Most 8-pin connectors should be able to withstand such current, even if it's technically past specification.
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