PSU for 2 4890's xfire

[masscrazy]

I currently have a 520W PSU and that wont do.

Im looking to this 850W NorthQ Black Magic Flex Modular Green PSU @£70

I've looked at the reviews on JohnnyGuru and other sites, as well as 3dgameman. All says its fine, does wat its supposed to, well.

Its costing at least £25-£35 less than say a Corsair/Antec PSU.

Should i go for it?

[tombull]

I've got an almost identical rig to yours with a few more hard disks in it. I've been thinking about upgrading to dual graphics cards but I'll also probably need to upgade my PSU (OCZ StealthXtreme 600W) to cope. These are the things I've considered:

• The second PCI-E slot only runs at x4 speed. This will seriously limit the bandwidth to the second graphics card. I have an old card in that slot at the moment (ATI Radeon X700 or something) just so I can run a third screen. This setup works OK, but I'm not sure it's going to be a great experience running a Crossfire graphics setup on this board.
• You need to consider the distribution of power accross the rails of the new PSU. The NorthQ PSU you are looking at seems to have a pretty odd distribution of power accross the rails: one rail goes to the CPU on one 4-pin 12V CPU line, one goes to the other 4-pin CPU line and the last two rails are joined for everything else (that means both graphics cards, the rest of the motherboard and all peripherals. Other PSUs have separate 12V rails for each of the graphics cards, which might be better suited to what you need, or even better, one huge 12V rail that supplies everything. In that case, you know that if the single rail is big enough, then it will handle any type of setup.

Sorry I can't provide any definite answers, but I hope I've given you some things to think about...
Tell me how it goes - as I said, I'm thinking of a similar upgrade in the near future...

[Terbinator]

Won't a 650/750W Corsair unit do it for around the same price ?

[Ulti]

The PSU does indeed have good reviews, it's also on Scan's Today Only for around £65 which seems like an amazing deal to me. Not to mention it's also modular, which for me is added value.

[shadowmaster]

I've got an almost identical rig to yours with a few more hard disks in it. I've been thinking about upgrading to dual graphics cards but I'll also probably need to upgade my PSU (OCZ StealthXtreme 600W) to cope. These are the things I've considered:

You could quite easily get away that psu. I'm running the same psu with a 4870X2, 3 hard disks and an overclocked Q6600

[tombull]

You could quite easily get away that psu. I'm running the same psu with a 4870X2, 3 hard disks and an overclocked Q6600

I might just give it a go with my current PSU. It does have 2x PCI-E cables after all. They are only 6-pin though, so 2x4870 wouldn't be possible (as most require 2x6-pin connectors EACH!). Maybe going the 4870X2 route is the best thing to do... What power connectors does your graphics card require?

[masscrazy]

I've got an almost identical rig to yours with a few more hard disks in it. I've been thinking about upgrading to dual graphics cards but I'll also probably need to upgade my PSU (OCZ StealthXtreme 600W) to cope. These are the things I've considered:

• The second PCI-E slot only runs at x4 speed. This will seriously limit the bandwidth to the second graphics card. I have an old card in that slot at the moment (ATI Radeon X700 or something) just so I can run a third screen. This setup works OK, but I'm not sure it's going to be a great experience running a Crossfire graphics setup on this board.
• You need to consider the distribution of power accross the rails of the new PSU. The NorthQ PSU you are looking at seems to have a pretty odd distribution of power accross the rails: one rail goes to the CPU on one 4-pin 12V CPU line, one goes to the other 4-pin CPU line and the last two rails are joined for everything else (that means both graphics cards, the rest of the motherboard and all peripherals. Other PSUs have separate 12V rails for each of the graphics cards, which might be better suited to what you need, or even better, one huge 12V rail that supplies everything. In that case, you know that if the single rail is big enough, then it will handle any type of setup.

Sorry I can't provide any definite answers, but I hope I've given you some things to think about...
Tell me how it goes - as I said, I'm thinking of a similar upgrade in the near future...

Hmm, the second bullet point kind of went over me head. So your saying it is good?

Also I'm actually getting a new motherboard because im getting two 4890's. My P5K-E as you say only has the x4 second PCIE at version 1.0. So thats why im going for a new mobo, thats why i need a new psu, and now a case (got the ram and should be getting a cpu with the mobo) The motherboard is a Gigabyte GA-X48-DS5. Was not planning on a new build but oh well.

Won't a 650/750W Corsair unit do it for around the same price ?

Well i just checked actually corsair 650W seems to be at £62 Today Only. Except it doesnt have 4 PCI-E connectors.

The PSU does indeed have good reviews, it's also on Scan's Today Only for around £65 which seems like an amazing deal to me. Not to mention it's also modular, which for me is added value.

Ooooh, ok so which is it. The corsair at £62 with 650W (without 2 extra PCIE connectors) or the NorthQ 850W for £65????

[Nanek]

The corsair has a single 12v rail doesn't it? would that not be more stable as the 12v has all that power going through only one whereas the north would have it all shared. I personally would get the corsair for the single rail.

[Terbinator]

The corsair has a single 12v rail doesn't it? would that not be more stable as the 12v has all that power going through only one whereas the north would have it all shared. I personally would get the corsair for the single rail.

That was my reasoning, just incase it wasn't clear i did mean the non-modular ones as they have 1 powerful rail and also a damn sight cheaper too!

[masscrazy]

That was my reasoning, just incase it wasn't clear i did mean the non-modular ones as they have 1 powerful rail and also a damn sight cheaper too!

Not in this instance, modular is cheaper.

But i will not be using the entire 850W max i think will be 650W so does it make it (NQ 850W) worth it?

[shadowmaster]

I might just give it a go with my current PSU. It does have 2x PCI-E cables after all. They are only 6-pin though, so 2x4870 wouldn't be possible (as most require 2x6-pin connectors EACH!). Maybe going the 4870X2 route is the best thing to do... What power connectors does your graphics card require?

One 8 pin and one 6 pin.

[Biscuit]

I personally would never buy anything i was a bit unsure about. Always have to bear in mind with power supplys that it is connected to everything in the computer and if it goes it could take everythign with it which costs a lot more than the £10-15 extra you could spend before hand for that peace of mind.

[masscrazy]

Can someone explain the rails system...
Wattage: 850 W
+12V1 Rail : 25 A
+12V2 Rail : 25 A
+12V3 Rail: 25 A
+12V4 Rail: 25 A
+12V5 Rail: N/A
+12V7 Rail: N/A
+12V8 Rail: N/A

I realise all amperage should be on single rails for reliability. But having them split like this on several rails means this PSU is unreliable?

[CAT-THE-FIFTH]

I would have a look at either of these two Antec modular units:

http://www.scan.co.uk/Products/650W-...Silent-Fan-PSU

http://www.scan.co.uk/Products/750W-...-80plus-Bronze

Both units have got excellent reviews from jonnyguru:

http://www.jonnyguru.com/modules.php...Story&reid=113

http://www.jonnyguru.com/modules.php...Story&reid=140

[masscrazy]

I would have a look at either of these two Antec modular units:

http://www.scan.co.uk/Products/650W-...Silent-Fan-PSU

http://www.scan.co.uk/Products/750W-...-80plus-Bronze

Both units have got excellent reviews from jonnyguru:

http://www.jonnyguru.com/modules.php...Story&reid=113

http://www.jonnyguru.com/modules.php...Story&reid=140

So did the NorthQ 850W, its only £65! These are in the £90's. And they dont have 4 pci-e connectors.

[CAT-THE-FIFTH]

So did the NorthQ 850W, its only £65! These are in the £90's. And they dont have 4 pci-e connectors.

The NorthQ does have a lower score and the capacitors seem to be from an unknown company. However it does look good value for money although 850W is a bit OTT though!!