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Finally pulled the trigger on TRI-SLI

Xaanix
Level 7
I went x79 with the intention on eventually going TRI-SLI. This week i saw an open box 680 signature on amazon for $407. Tax free with free shipping, this was a pretty good deal, especially considering amazon offers returns (craigslist and ebay have been selling these cards for the same amount with less favorable terms, such as added shiping or no returns. So props to amazon.

Card arrived in 2 days and it was actually brand new (just the box was damaged). I dug out my 3 way SLI connector from my R4F box and dropped the card in after wiring up my booster 3x. Booted up with no problems. Enabled SLI, (single screen) and tested Heaven at max settings and was getting 110+ fps. Switched to tri-screens, enabled fraps and precision, and played some crysis2. No problems so far, and with Crysis 2 on extreme settings at 5140x1050 i'm getting around 70 fps. Temps were ok (around 75 tops) and gpu utilization across all 3 cards was above 90%. (good!)

Question:
gtx680 has an 8 and also a 6 pin port. My psu has only 2 *8* pin and 4 6 pin pcie connections.

I have 2 options available to me:
1. the booster 3x has 2 6 pin outputs. I converted one of those 6 pin outputs to an 8 pin output via a connector. I then plugged that converted 8 pin, + the 6 pin from the booster directly into the card such that the entire 3rd card is powered only by the booster. This is my current state.
2. As an alternative, i could take both 6 pin outputs of the booster 3x and convert them into 1 8 pin (using a 2 to 1 adapter) then take one of the free 6 pin connectors from my psu for the other.

The psu is in my sig. keep in mind the psu is powering 2 other gtx 680s (by itself) as well as the cpu which has a minor overclock (4.3ghz).

which would be a better option? Someone mentioned problems with the booster 3s..
i'm thinking 300w from this device should be enough to handle one card by itself but if the units arent reliable maybe i shouldnt tax it so hard.
Motherboard Asus ROG Rampage IV Formula x79
CPU Intel i7 4820k Ivy Bridge-E @ 4.6ghz
GPU(s) 3 WAY SLI -- EVGA GTX 680 SC Signature (2GB)
Displays 5140x1050 @ 120hz using 3 x Samsung 2233RZ
RAM 16 GB 2133mhz G.Skill RipJaws Z
PSU LEPA G Series G1600-MA
Case Cooler Master Cosmos II Ultra
Storage Vertex 3 256 (Games), Intel 320 Series 128 (OS), + 4TB HDD
8,071 Views
14 REPLIES 14

Chino
Level 15

In what way is the rig at risk, is it the entire thing or just the 1 680 that's at risk?

What's the nature of the defect? fire? short? fried components?

also does anyone know what the actual draw against the 8 pin and 6 pin inputs are when a 680 is near max load?
Motherboard Asus ROG Rampage IV Formula x79
CPU Intel i7 4820k Ivy Bridge-E @ 4.6ghz
GPU(s) 3 WAY SLI -- EVGA GTX 680 SC Signature (2GB)
Displays 5140x1050 @ 120hz using 3 x Samsung 2233RZ
RAM 16 GB 2133mhz G.Skill RipJaws Z
PSU LEPA G Series G1600-MA
Case Cooler Master Cosmos II Ultra
Storage Vertex 3 256 (Games), Intel 320 Series 128 (OS), + 4TB HDD

Chino
Level 15
While we're on the topic of electronics, all the above that you mentioned can happen. Personally I just prefer my power source coming from a single device rather than 2 or 3.

As for the power draw, a single 6 pin PCIe connector can deliver up to 75W while a 8 pin PCIe connector can do 150W.

Xaanix
Level 7
Yeah i've read that in the past... i've also read that the extra 2 pins are just grounds..
Motherboard Asus ROG Rampage IV Formula x79
CPU Intel i7 4820k Ivy Bridge-E @ 4.6ghz
GPU(s) 3 WAY SLI -- EVGA GTX 680 SC Signature (2GB)
Displays 5140x1050 @ 120hz using 3 x Samsung 2233RZ
RAM 16 GB 2133mhz G.Skill RipJaws Z
PSU LEPA G Series G1600-MA
Case Cooler Master Cosmos II Ultra
Storage Vertex 3 256 (Games), Intel 320 Series 128 (OS), + 4TB HDD

Chino
Level 15
Let's break down the numbers.

A 6 pin PCIe connector has three +12V wires. The maximum current per wire is 2.083A. So when we apply Ohm's/Watt's Law (12V x 2.083A), we get a total 24.996W per wire. We multiply that by 3 because we have three wires which brings the total wattage per 6 pin PCIe connector to 74.988W rounded off to 75W.

But is 2.083A the maximum that each +12V wire can draw? No. Actually they can pull double the current (4.166A) but to be able to achieve that they needed to add 2 more ground wires to handle the extra current. So the 8 pin PCIe power connector can support up to 149.976V (3 x 12V x 4.166A). But since people like rounding stuff, 150W.

so the 6 to 8 pin converter is going to overtax the thing more than anything else then right?

will those wires run too hit if they're sinking all that current?

isnt a 6 to 8 pin adapter really the same as a 6+2? those are common on alot of power supplies that run 4 way sli... so those should be capaable of 150 watts no?
Motherboard Asus ROG Rampage IV Formula x79
CPU Intel i7 4820k Ivy Bridge-E @ 4.6ghz
GPU(s) 3 WAY SLI -- EVGA GTX 680 SC Signature (2GB)
Displays 5140x1050 @ 120hz using 3 x Samsung 2233RZ
RAM 16 GB 2133mhz G.Skill RipJaws Z
PSU LEPA G Series G1600-MA
Case Cooler Master Cosmos II Ultra
Storage Vertex 3 256 (Games), Intel 320 Series 128 (OS), + 4TB HDD

so i guess what i'm asking is, what is the difference between having a 6 pin to 8 pin adapter ( http://www.amazon.com/StarTech-Express-Power-Adapter-PCIEX68ADAP/dp/B001TK3TJY/ref=sr_1_1?ie=UTF8&qi... ) compared to having 6+2 connectors from a power supply such as this: http://www.newegg.com/Product/Product.aspx?Item=N82E16817494006

are those ground wires from the 6+2's wired through to the psu or do they just connect into the other grounds?

Based on what you are saying i'd think that the danger here is that the wires would get hot from being forced to handle to too much current (whlie themselves beeing too thin to handle it, thus getting hot)
Motherboard Asus ROG Rampage IV Formula x79
CPU Intel i7 4820k Ivy Bridge-E @ 4.6ghz
GPU(s) 3 WAY SLI -- EVGA GTX 680 SC Signature (2GB)
Displays 5140x1050 @ 120hz using 3 x Samsung 2233RZ
RAM 16 GB 2133mhz G.Skill RipJaws Z
PSU LEPA G Series G1600-MA
Case Cooler Master Cosmos II Ultra
Storage Vertex 3 256 (Games), Intel 320 Series 128 (OS), + 4TB HDD

Chino
Level 15
The 8 pin PCIe connectors varies from one PSU to another. Some manufacturers bridge them off the other grounds like this one here.


While other manufacturers run them directly from the PSU itself like this one here.


I've seen a lot of users have use those 6 pin to 8 pin adapters like the one you linked and they've had no hiccups or any misfortunes. But being the paranoid guy that I am, I tend to avoid adapters. LOL

Xaanix
Level 7
my psu has the top style.. 😕 This is why i wasnt clear as to the benefit of 6+2's in general, as to me it seemed the same as having an adapter.

happen to know which style this psu has?
http://www.amazon.com/LEPA-1600-Watts-Crossfire-Certified-G1600-MA/dp/B007W5TV6K/ref=sr_1_1?ie=UTF8&...
Motherboard Asus ROG Rampage IV Formula x79
CPU Intel i7 4820k Ivy Bridge-E @ 4.6ghz
GPU(s) 3 WAY SLI -- EVGA GTX 680 SC Signature (2GB)
Displays 5140x1050 @ 120hz using 3 x Samsung 2233RZ
RAM 16 GB 2133mhz G.Skill RipJaws Z
PSU LEPA G Series G1600-MA
Case Cooler Master Cosmos II Ultra
Storage Vertex 3 256 (Games), Intel 320 Series 128 (OS), + 4TB HDD