# 6-pin PCI-E power connector when GPU has 8-pin slot?



## SonicZap (Jul 5, 2015)

Hey,

I'm assembling a secondary system consisting of old parts from family members. We have a Asus Radeon HD 5770 (I can't remember the exact model) that has a 8-pin power connector and a 6-pin power connector. The PSU only has 2 6-pin power connectors. Is it a good idea to try it with the 2 6-pin power connectors despite one of the graphics card's connectors having two additional pins? The HD 5770 takes relatively little power IIRC, I'm wondering why it even has so many power connectors.

The PSU in question is a "Modecom Premium 500W". Sounds shady, but it was bought in 2010 and it has run a system fine for 4½ years.


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## FordGT90Concept (Jul 5, 2015)

I wouldn't.  Even though the last two pins are only grounds, the power supply isn't set up to provide that much power to it (I believe it is about 100w difference between 6 and 8).  I'd definitely play it safe and upgrade the power supply.


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## CAPSLOCKSTUCK (Jul 5, 2015)

there are these








and these





i have an XFX hd 5770 and it has 1x 6 pin


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## FordGT90Concept (Jul 5, 2015)

I wouldn't use those but I would consider one of these:
http://www.avadirect.com/Two-6-pin-PCIe-Power-to-8-pin-PCIe-Power-Adapter-Cable/Product/3762008




Might be very hard to find in Finland though.


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## CAPSLOCKSTUCK (Jul 5, 2015)

FordGT90Concept said:


> I wouldn't use those but I would consider one of these:
> http://www.avadirect.com/Two-6-pin-PCIe-Power-to-8-pin-PCIe-Power-Adapter-Cable/Product/3762008
> 
> 
> ...




it sounds like he has 2 x 6 pin available so your one wont work


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## SonicZap (Jul 5, 2015)

I'd rather avoid all kinds of converters, but I don't want to spend extra money on these parts either. Hmm. The TDP of the HD 5770 is only 108W. I'd assume that Asus has applied a factory OC which will increase the power consumption a bit, but still, 75 W from the PCI-E slot should mean that the graphics card only needs ~40W from the power connectors. And one 6-pin power connector can provide 75W. With the two the PSU has, it should (in theory) be able to provide 150W. With this math it sounds like I shouldn't get any issues, in practice it could be different though..


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## CAPSLOCKSTUCK (Jul 5, 2015)

Use one of these, you will be fine. They can be bought for as little as 99p UK


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## Aquinus (Jul 5, 2015)

Given the off-brand PSU and the lack of adequate connectors, I'm with @FordGT90Concept on this one. I wouldn't tempt fate. However, my 6870s take two 6 pin connectors and my parents have a 5770 in their machine that only takes a single 6-pin connector. Either way, if the GPU is overclocked OOTB, that might explain it.

Honestly, I'm uncertain which is why I'm with Ford. It sounds weird that a 5770 would want that much power but on the other hand, the PSU seems shady to me so do you really want to risk it? I personally wouldn't.


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## Norton (Jul 5, 2015)

I would check that card first- no 5770 that I know of has a 6pin and an 8pin power connector on it. If it does have them then you likely have a *5870 *not a 5770.


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## SonicZap (Jul 6, 2015)

So, I took a risk earlier on and it runs well. I started suspecting the "5770" as well, and Norton was close; it's actually a HD 5830 (I only found it out after the system booted and I ran GPU-Z, awesome piece of software). However, the system appears to work properly, and that includes running demanding (for the card's standards) games.

If the PC had new parts I wouldn't have risked it with that PSU, but since it's a PC built from expendable extra parts I decided to try it out. Everything appears to be fine now  Thanks for the replies.


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## CAPSLOCKSTUCK (Jul 6, 2015)

How did you solve the 8-pin problem?


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## SonicZap (Jul 6, 2015)

CAPSLOCKSTUCK said:


> How did you solve the 8-pin problem?


I didn't. I just plugged those two 6-pin power connectors into the card, meaning that it now has a 8-pin power slot that only has a 6-pin power connector plugged into it. Maybe it could cause trouble under FurMark or something, so far there's been no issues though.


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## HWTactics (Jul 6, 2015)

SonicZap said:


> I didn't. I just plugged those two 6-pin power connectors into the card, meaning that it now has a 8-pin power slot that only has a 6-pin power connector plugged into it. Maybe it could cause trouble under FurMark or something, so far there's been no issues though.


Interesting.  I've never tried that before on a video card (and don't plan to) so let us know if it goes belly up.


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## RealNeil (Jul 6, 2015)

I'm glad that it worked for you Zap. Lucky that it did.


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## hat (Jul 6, 2015)

When PCI-E 8 pin first came about I remember something about people bending a paper clip and stuffing it in the additional 2 spots so as to trick the card into thinking there was an 8-pin plugged in. I would be quite weary trying that though...


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## RealNeil (Jul 6, 2015)

hat said:


> When PCI-E 8 pin first came about I remember something about people bending a paper clip and stuffing it in the additional 2 spots so as to trick the card into thinking there was an 8-pin plugged in. I would be quite weary trying that though...



Now ~that~ would take some balls to do!


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## SonicZap (Jul 6, 2015)

I kinda doubt the card "cares" how many pins are connected as long as it's getting enough power. In this case, it appears that it's getting enough power, at least under typical (gaming) loads.


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## FordGT90Concept (Jul 6, 2015)

As long as the PSU holds up, I think it should be fine.  5830 shouldn't need an 8-pin at all unless it was only an 8-pin (no additional 6-pin).


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## OneMoar (Jul 6, 2015)

would be fine if that psu was up to snuff but would't trust it


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## brandonwh64 (Jul 7, 2015)

I had the same issue at work with my 7970. PSU was a 700W server PSU with only two 6pin PCI slots and the card had one 6 pin and a 8 pin so I ran two jumpers from two separate unused molex connectors and it works like a champ but I trust the PSU


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## de.das.dude (Jul 7, 2015)

I wouldn't run a 5380 off a 500w, specially from a weird brand.
ive had lots of trouble with cheap branded PSUs in the past


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## thebluebumblebee (Jul 7, 2015)

> ASUS has decided to put one six-pin and one eight-pin connector on their card. In our power testing we saw a maximum power draw of 146W, so this is mostly for show.


From w1zzard's review, Asus HD5830


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## thebluebumblebee (Jul 7, 2015)

Here's the "reason" for the 6+8 pin configuration:


> ASUS Exclusive Voltage Tweak Technology for up to 50% performance{boost}





> Power Consumption: up to 225W2 additional 6 pin PCIe power required


The one thing that I don't like about w1zzard's reviews is that he does not show OC'ing wattage, which I can partially understand because there are so many factors that can effect the results.  So, back to the card at hand.  *IF* a person over-volted and *IF* a person over-clocked this card to the *extreme*, there could be a need for the connectors provided.  I will applaud ASUS for being so conservative, as 2x 6 pin PCI-e power connectors can provide up to 225 watts but using 6+8 pin bumps the power supplied to 300 watts.
Remember when?:


> All these changes result in a fairly low performance per Watt result when comparing the HD 5830 to all other cards of the HD 5000 Series. However, compared to the rest of the market, the perf/Watt score is still excellent, *leaving most NVIDIA cards behind by over 15%*.


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## RejZoR (Jul 8, 2015)

The Corsair HX750 that I have has a modular 6 to 8 pin. It has 6 pins and 2 extra that can be detached. I've used 2x 6pin for HD7950, for GTX 980 I'm using 1x8 pin (6+2) and 1x8 pin. Donno how that is done on cheaper PSU's...


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## SonicZap (Jul 10, 2015)

Well, it worked fine for a few days, then suddenly it started rebooting by itself, with the BIOS saying that the system was shut down to protect itself from voltage spikes from the power supply. Meh. Swapped the PSU to a 430 W Antec Neo-HE and the GPU to a Radeon HD 4850. Hopefully it works now.

The CPU is a Pentium G3258 (not overclocked), so I think 430W should suffice. Especially since it's a known good brand this time.


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## Mussels (Jul 10, 2015)

SonicZap said:


> Well, it worked fine for a few days, then suddenly it started rebooting by itself, with the BIOS saying that the system was shut down to protect itself from voltage spikes from the power supply. Meh. Swapped the PSU to a 430 W Antec Neo-HE and the GPU to a Radeon HD 4850. Hopefully it works now.
> 
> The CPU is a Pentium G3258 (not overclocked), so I think 430W should suffice. Especially since it's a known good brand this time.



the total wattage of the system would be quite low, just that cheap no-name brand PSU's tend to be total and utter garbage (600W PSU that can only provide 200W, that sort of crap)


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## revin (Jul 10, 2015)

brandonwh64 said:


> I had the same issue at work with my 7970. PSU was a 700W server PSU with only two 6pin PCI slots and the card had one 6 pin and a 8 pin so I ran two jumpers from two separate unused molex connectors and it works like a champ *but I trust the PSU*


 


de.das.dude said:


> I wouldn't run a 5380 off a 500w, specially from a weird brand.
> ive had* lots of trouble with cheap branded PSUs* in the past





Mussels said:


> *the total wattage of the system would be quite low, just that cheap no-name brand PSU's tend to be total and utter garbage (600W PSU that can only provide 200W, that sort of crap)*


 


SonicZap said:


> Well, it *worked fine for a few days*, then suddenly it started rebooting by itself, with the BIOS saying that the *system was shut down to protect itself from voltage spikes from the power supply.* Meh. Swapped the PSU to a 430 W Antec Neo-HE and the GPU to a Radeon HD 4850. Hopefully it works now.
> 
> The CPU is a Pentium G3258 (not overclocked), so I think 430W should suffice. Especially since it's a known good brand this time.


 
This Post should be used to point people to when they are trying to use cheap build PSU's 
Classic example, with proof of the need for a quailty PSU......also very good BIOS, that indeed told just what was wrong !!!


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## brandonwh64 (Jul 10, 2015)

revin said:


> This Post should be used to point people to when they are trying to use cheap build PSU's
> Classic example, with proof of the need for a quailty PSU......also very good BIOS, that indeed told just what was wrong !!!



The PSU I am using is of very high quality due to being made to run 24/7 in a server environment. It has plenty of wattage and amperage but was limited to 6Pin PCIex since most servers do not have the need for that.


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