PSU for 3x VTX3D R9 280x cards

[radi324]

Hey there - is a 1000W Gold-standard PSU enough for 3 of these cards, AMD Sempron CPU and 3x powered PCIe risers? The PSU I was looking at is the Corsair RM1000:

http://www.corsair.com/en/power-supply-units/rm-series-power-supply-units/rm-series-rm1000-80-plus-gold-certified-power-supply.html

I was also looking at the Corsair AX1200 PSU (1200W) but it costs 100 euro more than the RM1000, and if I don't need 1200W, might as well go for the RM1000. Thanks!

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[pryzh]

I have 3 Vapor X R9 280x running well on a Lepa 1000w Gold PSU. 1000w should be enough as long as the PSU is gold rated and can deliver at least 900w on peak power output. Also you need to consider that you will not be able to overclock your cards much from stock as then you simply wont have enough power.
Also another point is to ensure your PSU has at least 6 of the 8pin cables to power the video cards as you need 2 per card.
I had a Silverstone 1200W G Strider GOLD PSU that had only 4 8pin cables, so i ran the other 2 via the molex adapter supllied with the card, however the wires on the molex turned out to be too weak and the modular connections on the PSU have melted and made these 2 connectors unusable.
After that i got a LEPA 1000w Gold PSU which has 6 8pin connectors and was only 139 euro!!

[radi324]

Thanks for the heads up, didn't know about that! I just read about the AX1200 review on jonnyguru:

http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story&reid=189

Says that there are "6+2 pin PCIe (610mm)   6" slots

So I'm assuming that there's enough for 3 280x. Also, the pictures show 8 8-pin connectors, and I assume that there are enough cables as well... wouldn't make any sense for them not to provide enough cables

[pryzh]

Yep that one will do you perfect, Plus its the AX which are not the budget series so you should get very very stable performance out of this one. Im pretty sure that you could even run 4 with this one, but would need to consider how you gonna power your cards as it comes with only 6 8pin cables.
The 8 slots which are 8 pin that you see on the PSU are the modular connectors. 2 of them are used for 8 pin CPU 12v power.

The only downside of this PSU is the price! When i was looking for a PSU i did consider this one, but it was a bit outta budget, so i went with the LEPA 1000w and have no regrets so far! Also LEPA is almost half the price of this PSU.

[radi324]

Well, the other option I was considering was this one:

http://www.corsair.com/en/power-supply-units/rm-series-power-supply-units/rm-series-rm1000-80-plus-gold-certified-power-supply.html

The only thing I'm afraid of is that I might max out the power on this PSU. I mean, it'd be under warranty and everything, but I don't know how far I'd have to OC the cards in order to pass the 700kh/s mark. What's your current KH/s on that PSU? Are temps stable btw?

[pryzh]

These 3 are running at around 725/730 kh/s each. Funny thing is i had to underclock in order to get these. Current speeds are 1045/1500 while the card came with 1070/1600, with the default clocks i get 670-680 kh/s per card.
I guess it would also depend on the make and if its made using the ref design.
Unless you will be clocking above 1100/1650 or around there, in my opinion your RM psu should not be maxed out.
I never had any of the RM series PSUs so cant say how well it does, but its corsair so it should be very good one.
The temps of my cards in the rig are 80/73/67 the reason for that is that 2 cards are in the board and one is hanging on the rack. So 2 of them are very close to each other, but the temps are stable at above and are not a cause of concern.

[radi324]

Well, thanks a lot for your help! I'll be going for the Corsair RM1000 PSU, since I'll be undervolting the cards. Do risers affect the PSU draw in anyway? I'll be using 3 of these risers:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=271373085981&ssPageName=ADME:L:OC:US:3160

No DVD-RW, 320GB HDD SATA, might attach monitor to one of the cards to check on things.

[radi324]

Thanks for moving my topic mods, didn't know it was in the wrong section! Any other insights just to get a second opinion on my question would be appreciated

[Hippievogel]

Hey there - is a 1000W Gold-standard PSU enough for 3 of these cards, AMD Sempron CPU and 3x powered PCIe risers? The PSU I was looking at is the Corsair RM1000:

http://www.corsair.com/en/power-supply-units/rm-series-power-supply-units/rm-series-rm1000-80-plus-gold-certified-power-supply.html

I was also looking at the Corsair AX1200 PSU (1200W) but it costs 100 euro more than the RM1000, and if I don't need 1200W, might as well go for the RM1000. Thanks!

you dont want to go for the RM1000, i got several psu's and even with 0.10dollarcent a kwh its worth to go for the ax860/ax1200. the efficiency on higher loads(65%-90% load) the rm1000 drops with atleast 3%
remember there are 8760 hours in a year saving 10watts is 80kwh.
look at the graph
Rm1000
http://cwsmgmt.corsair.com/media/cms/psu_charts/RM1000-EFFICIENCY.png
Corsair ax1200
http://cwsmgmt.corsair.com/media/catalog/product/a/x/ax1200i-efficiency.png

as you can see the range of all loads stay above 90% on the ax1200 the rm1000 on the other hand drops like a rock after 55% and up load.

[bmL]

I have 3 Vapor X R9 280x running well on a Lepa 1000w Gold PSU. 1000w should be enough as long as the PSU is gold rated and can deliver at least 900w on peak power output. Also you need to consider that you will not be able to overclock your cards much from stock as then you simply wont have enough power.
Also another point is to ensure your PSU has at least 6 of the 8pin cables to power the video cards as you need 2 per card.
I had a Silverstone 1200W G Strider GOLD PSU that had only 4 8pin cables, so i ran the other 2 via the molex adapter supllied with the card, however the wires on the molex turned out to be too weak and the modular connections on the PSU have melted and made these 2 connectors unusable.
After that i got a LEPA 1000w Gold PSU which has 6 8pin connectors and was only 139 euro!!

That if PSU will handle does not depend on the fact if PSU is gold/bronze/platinum etc. .
If You have good 1000W psu without 80+ (let's say its 60% effective) it will give max 1000W but at the same time it will consume 1400W at peak (1000W+1000W*(100-60)%)
If You have good 1000W gold 80+ psu (let's say its min 90% effective) then it will also give max 1000W but will consume only 1100W at peak.

So... if PSU is 1000W and it's not 80+ it still can deliver 1000W (if it's good brand) it will simply consume more power. The extra power (eg. 400W) is lost for example by heating up PSU.

[atp1916]

Thanks for the heads up, didn't know about that! I just read about the AX1200 review on jonnyguru:

http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story&reid=189

Says that there are "6+2 pin PCIe (610mm)   6" slots

So I'm assuming that there's enough for 3 280x. Also, the pictures show 8 8-pin connectors, and I assume that there are enough cables as well... wouldn't make any sense for them not to provide enough cables

I have 2 of these AX1200's, and there are indeed 3 6x2 pice connectors...but not 4. The unit does come with 9 billion molex / sata connectors, so molex converters one will need.