650W enough for 2-card mining rig?

[AngelusWebDesign]

For a mining rig (no sound card, DVD activity, etc.) that uses about 100W -- I don't plan on CPU mining -- plus (2) 5830, what size power supply should I get?

Conventional wisdom says "500W for a one-card system, 750W for a 2 card system"

I know that you don't want to hit the limit exactly, because most power supplies CAN'T handle their advertised maximum.

But how close can I hope to get? I'm planning on buying a quality power supply -- not the cheapest I can find. You get what you pay for, and there are some areas you don't want to skimp.

200W + 200W + 100W = 500

So a 620 or 650 should be sufficient, right?

I ask because a 650W (decent brand) can be had for $49 after rebate, whereas a good 750W (I keep coming back to Corsair here for some reason) will set you back $95 or more. That's a big difference!

Any miners out there try that configuration yet?

Thanks,

Matthew
 

[1715180596]

1715180596

[trueimage]

5830 will draw 165w-175w under load at stock each

I'd get an 80+ GOLD rated PSU so you are wasting as little power as possible

[AngelusWebDesign]

Looking over the options, it looks like most 650 and 630W power supplies only have TWO PCI-E connectors -- which would only power (1) 5830.

So that's the real problem -- what's the cheapest quality power supply that has (4) PCI-E connectors?

I'm afraid it's the Corsair 750 -- which is $95 after rebate.

Considering that a 500W power supply can be had for $35, is a 2-card rig even more cost-efficient?  Barely.

[Nilarium]

Looking over the options, it looks like most 650 and 630W power supplies only have TWO PCI-E connectors -- which would only power (1) 5830.

So that's the real problem -- what's the cheapest quality power supply that has (4) PCI-E connectors?

I'm afraid it's the Corsair 750 -- which is $95 after rebate.

Considering that a 500W power supply can be had for $35, is a 2-card rig even more cost-efficient?  Barely.

why u cant just use connectors molex ::> 6 pin

[trueimage]

Looking over the options, it looks like most 650 and 630W power supplies only have TWO PCI-E connectors -- which would only power (1) 5830.

So that's the real problem -- what's the cheapest quality power supply that has (4) PCI-E connectors?

I'm afraid it's the Corsair 750 -- which is $95 after rebate.

Considering that a 500W power supply can be had for $35, is a 2-card rig even more cost-efficient?  Barely.

why u cant just use connectors molex ::> 6 pin

yeah, do this. Just make sure you get a quality PSU with good efficiency, whatever you do.

http://www.hardocp.com/reviews/psu_power_supplies/
http://www.jonnyguru.com/modules.php?name=NDReviews&op=Review_Cat&recatnum=13

[smoki]

A quality 650W psu should be able to supply at least 600 of those Watts on the 12V rail, which is the one that's actually powering pretty much everything in today's systems.
A 5830 has a specified tdp of 175W. Mining doesn't utilize the whole gpu so power consumption during mining should probably be a bit lower. If you downclock the memory to 200-300MHz range you save about 15W per card. So a 5830 at stock gpu and underclocked memory should pull about 150W while mining. Overclocking without overvolting will raise that back to maybe 170W.

So, a quality 650W psu should be able to power 3 5830s, not just 2, with about 100W left over for the rest of the system. Downclock and undervolt your cpu and that should be plenty of W to spare.

[AngelusWebDesign]

I forgot about that -- you can convert a molex to a PCI-E connector -- I think I have a couple of those.

Matthew

[Bitonetta]

It'll be fine.  Most your cards will pull is ~200w OC.  That's being very [very] conservative.  2 should be no problem as long as your other parts aren't crazy.  But I'm not sure I would take 3 on it.  That's alittle too close for me tho.  I usually get one 'tier' higher then what max I'll need just in case.