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Using a PCI-E Connector

Drake5

Drake5

Drake5

Soldato
Joined
12 Dec 2005
Posts
14,577
The graphics card I'm getting needs 2 X PCI-e connectors. My XFX 450W only has the one so I've got to add a 4-pin molex connector.

I've read around and people saying to have the connector on a 'dedicated' 4 pin molex, I'm not fully sure what this means.

On my PSU I have 1 cable that has 4 seperate molex connections, do people mean just connect the PCI-e adapter and nothing else to the molex or do they mean just make sure the PCI-e connector is running off a single molex and not crossed with a bunch of fans etc?

Cheers
 
what graphic card you plan on using? what mb/cpu

its best to use power connectors coming off psu 4pin/6pin/8pin

depends on how power hungry the gpu is,you will be fine on a molex to 4pin adaptor if its not a power hungry card,otherwise your safer buying a psu that has all the connectors needed for sli/xfire or two 4 pin/6pin pci-e plugs
 
Is that the XFX core edition 450W?

If so, that PSU should have two PCIE power connections (according to the specs), one is the standard 6 pin type, while the other is a 6+2 pin type (but it works fine as a standard 6 pin, with the extra 2 cables unconnected).
 
Just getting ready to install the 5850 now and took another look on the PSU, I can indeed only see the one PCI-e adapter, it has a further 2 pin attached to it.

I also looked on the PSU box and it says '(1) PCI-E 6/8-pin'.

So I will have to use one of the PCI-E Adaptors that came with the 5850 - Would I be OK just adding it to a spare 4 pin molex coming from my PSU or as I said initially does it have to be on a line that has nothing else connected to any of the other molex's?

It's strange that the one you linked is exactly the same but the specs are a bit different? :S

Cheers
 
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That is strange - must be a different revision of the XFX 450W.

Yes, it would be fine to connect the molex to PCIE adapter from the PSU to the graphics card. Both use the 12V rail - so you are just swapping around a few of the pins.

Unless you are using that molex line to connect up a different graphics card then I reckon you should be fine using the adapter with a line of molex cables that is partially used. Since the standard applications for molex connections (HDDs, ODDs, fans) don't really use a lot of power.
 
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Cheers guys - On the one line of molexs I've got this:

3-4 fans connected together using just 1 molex and the other 2 molex are spare, so I just attached the PCI-E Adapter to one of the spare ones.

So this won't affect performance or anything?

Cheers
 
You should be fine with that arrangement.

Each of the PCIE 6 pin power connectors should be able to deliver up to 75W to the graphics card, in addition to the 75W provided by the PCIE slot. However, a standard HD 5850 only draws 151W. So you can expect each of the PCIE power connections to only draw ~38W at maximum load (ie. not very much).
 
Hi guys,

I ran 3dmark11

m7g03.png


Said my score is low compared to others, is it because most of the others seem to be overclocked?

Cheers
 
I think it is because of my card running at stock as I took a look and compared others and every one was overclocked... I do hope the pcie adapter I'm using wont affect performance any?

So, I believe the max overclock for a non-reference 5850 is 775/1125. Would I be safe going straight up to that overclock and then using something to stress test?

Thanks
 
I Overclocked to 775/1125, and got a better score in 3dmark.

Didn't mess with any fan settings in afterburner, running furmark burn in test now, and been going for five minutes, temp is at 90c fully loaded. Is this to hot?

Think it's getting so hot because my fan speed is on auto, what should I have it on guys? Running at 100% always?
 
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It is a bit hot, I would try and keep it under 80 degrees.

Having the fan on 100% will keep it cooler, but it will likely drive you mad with the noise.

Instead, you can setup a custom fan profile within afterburner which changes the fan speed with different temperature levels. Just click on "settings" on the main Afterburner page, then select the "Fan" tab, then tick the box to allow user defined fan profiles. From there you can make your fan profile graph however you like.
 
cmndr_andi said:
It is a bit hot, I would try and keep it under 80 degrees.

Having the fan on 100% will keep it cooler, but it will likely drive you mad with the noise.

Instead, you can setup a custom fan profile within afterburner which changes the fan speed with different temperature levels. Just click on "settings" on the main Afterburner page, then select the "Fan" tab, then tick the box to allow user defined fan profiles. From there you can make your fan profile graph however you like.
Click to expand...

Thanks - I'm having some bizare issues with the card.

I set the fan to run at 80% always while I tested out FurMark. No difference, it got straight up to 90c. As soon as the temp hits 90c, the GPU seems to throttle as quite a lot of performance is lost in FurMark after 90C.

I reset the overclock to stock settings and ran FurMark again. The GPU hit as high as 90c and seemed to throttle again.

I'm not sure what's going on, I have decent cooling in my case.

Any ideas?
 
To be honest, furmark isn't a particularly fair test on graphics cards - most graphics card companies consider it a "power virus" since it puts graphics cards under unrealistic loads and this can cause damage (due to excessive heat) - while the most intensive gaming load on the same card would be perfectly fine.

That said, i'm not really sure what a good alternative is for a GPU stress tester (hopefully someone reading the thread can suggest something) - perhaps running 3Dmark in a GPU -focused test.
 
Thanks - I ran furmark again with an overclock. The GPU is certainly throttling after 90c in furmark as I saw it in GPU-z. I can also hear the fan throttle really badly, it sounds like someone revving a car.

Really not sure what's going on, I don't think it's anything to do with the overclock as I have the exact same results and temp without it.

Cheers

EDIT - I tried MSI Kombuster aswell and that gets to 90c really fast without an overclock and just throttles.
 
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I think MSI kombustor uses the same same software as furmark - so it will also give you high temperatures very fast.

As you point out - once the card hits a set temperature it will throttle itself to prevent damage. The reason applications like furmark are not widely loved is because sometimes the throttling doesn't kick in fast enough and you get a bricked card.

Therefore, if you want to continue with the GPU overclocking I would recommend you either use a different application to load test it or you provide additional cooling to the card (maybe a 120mm fan aimed at the GPU fan intake) so that under load it is less likely to hit the temperature where throttling kicks in.
 
I have 2 X 120MM Fans on the side of my case that are situated over the GPU. I believe they are pulling air out of the case.

The 5850 was bought from the MM, the heatsink is a bit dust but I don't want to mess with anything like that just yet. Maybe it could do with having some new thermal paste applied aswell?

Just concerned if their may be anything wrong with the card, I know furmark is very demanding but should it really be heating a card up that fast?

Also I notice the back of the GFX Card has a strange white substance on some parts of it, not sure if that is anything significant?

Cheers
 
If those fans are pulling air out of the case then you may want to re-evaluate the airflow setup of your case - as if you could get those fans blowing air onto your card (while maintaining good airflow for the rest of your case) then it should help with the cooling of your graphics card (so hopefully lower temperatures at load).

As for the card itself - as it is second hand I would strongly recommend you give the heatsink a few blasts with some compressed air - as this will dislodge dust and help with cooling.

If you are confident with removing the cooler of the graphics card (or at least willing to learn) then this is likely to reduce your temperatures too. Usually graphics card manufacturers don't use the best thermals paste and almost always use way too much - so a re-apply of good quality paste should help with load temps.

As for the white substance, I'm honestly not sure. Could you upload a photo?
 
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