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PSU questions for this build...

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March 19, 2014 12:12:24 PM

I've gotten a lot of help here with a build I'm working on and it's almost together except for the PSU. (Build posted at end of this post) I'm willing to pay a little more for a quieter PSU, but I have a few questions.

1. How much PSU power? I've gotten recommendations here and from other places suggesting that my build wouldn't need more than a quality 550W PSU. However, the specifications listed for my vid card say a 750W PSU is REQUIRED. Is this something I should be concerned about or is 550W really adequate? I will mention that Anandtech did a good review of this vid card and when they ran it at load (furmark), they got a result of 413w. It was a different build than mine, but I offer it as a reference. I don't know if the 413w result was the power draw of the whole system or if they were somehow monitoring just the vid card. I don't plan to upgrade this PC but I do want peace of mind. Is 550W enough?
http://www.anandtech.com/show/7601/sapphire-radeon-r9-2...

2. I'm sure this is a noob question, but to be 100% clear, my R9 290 tri-x requires both a 75 Watt 6-pin PCI Express power connector as well as the 150 Watt 8-pin PCI Express power connector in order to be fully powered, right? Just hook those up with three 4-pin molex connectors, and I'm good, right?

3. I have the whole build except for the PSU. I've been waiting for a good deal. In the meantime, I have an old SeaSonic S12-500. This might be a crazy idea, but I was thinking I would just use this PSU while waiting to buy a new one. I'd like to test some of the other components I purchased to make sure they work before my 30 day return policy expires. Would it be okay if I ran this build with the S12-500 just to test the components? The idea would be that I wouldn't push it too hard. BTW, what happens if you run a build on an inadequate power supply?

I couldn't find the specs from the seasonic website, but here are some specs from newegg. I'm not even sure it has the right power connectors...
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Here are a few PSUs I'm considering:
Kingwin 550W
Corsair RM 650 or 750
Be Quiet Dark Power pro 550 (BN600)

Even if I don't need the higher wattage of some of these PSUs, some operate with no fan until 40-50% load meaning I'd have quieter performance.


My build, missing PSU:
-------------------------

Mobo: GA-B85-HD3:
http://www.gigabyte.com/products/product-page.aspx?pid=...

CPU: Xeon E3 1230 V3
http://ark.intel.com/products/75054/intel-xeon-processo...

GPU: Sapphire R9 290 Tri-x OC (100362-2SR)
http://www.sapphiretech.com/presentation/product/produc...

Case: Fractal Design R4

Memory: G.Skill DDR3 1600 2x8GB

HDD: 1TB Western Digital Blue

SSD: Samsung EVO 250GB

DVD: Lite-on

Xtra case fan: Antec TrueQuiet 140mm fan

CPU Cooler: Mugen 4 (SCMG-400)


OS: Win 8.1

More about : psu questions build

a b ) Power supply
March 19, 2014 12:19:18 PM

Power supplies tend to blow when you run a build on inadequate power. This can also in turn fry your expensive components. I would wait until you buy the power supply. I also would not recommend lower than an a 550W PSU for the R9 290. You do not want to use 3 Molex connectors, you want to use 4. 2x Molex to 8 pin PCIE on both. 1x Molex to 6 pin doesn't provide enough wattage (60W I believe, instead of 75)

http://forum-en.msi.com/faq/article/printer/power-requi...

Recommends 31A on the +12V rail and a 550W PSU minimum. This list compiled from a bunch of recommended sources on amperage/power requirements for video cards.

Hope that helps.

[Quick Edit]
Ahmadjon provided this in another thread for what happens when you use an insufficient PSU:
http://www.theregister.co.uk/2012/11/26/exploding_compu...

Your Seasonic PSU has barely 33A between its +12V1 rail (17A) and +12V2 rail (16A), I would strongly recommend giving yourself a little more headroom though, since your card is factory overclocked. It would start up if you just wanted to test and make sure your system posts, but I wouldn't personally do any extended gaming or heavy workloads at that power. Most of the PSUs you've linked are decent, just get an 80+ Bronze or better 550W.
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March 19, 2014 12:42:10 PM

Craig,

I'm still checking on those links, but if there's even a chance I could fry things I'll abandon my idea to run the old seasonic, although I was only planning on using it temporarily at low load...

I'm still confused about power connections (question #2). According the vid card "system requirements":
1X75 Watt 6-pin PCI Express power connector is required
1X150 Watt 8-pin PCI Express power connector is required.

The GPU board has two separate connections. One is 4. The other is 8.

The card came with two cables. The power side of the 6 pin connector end in a single molex 4-pin connector. The power side of the 8-pin connector ends with two molex 4-pin connectors.

It seems like you are saying there should be two 8-pin connectors on the vid card but it appears there is only a 6 pin and an 8 pin. Maybe I'm missing something obvious or the wrong cables were included or something.

I'm going to go explore those links you gave me, but I wanted to get this reply out first. Thanks for your help.


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Related resources
a b ) Power supply
March 19, 2014 2:20:44 PM

Okay, so here's what I'm understanding of what you're asking.

Your card has a 6 pin PCIE Connector, and an 8 Pin PCIE Connector.
You have a cable that has 1x 4-pin MOLEX that goes to a 6-pin PCIE connector, like this:
http://www.exegate.com/images/catalog/400/pciex.jpg
It also has an 2x 4-pin Molex to 8-pin PCIE connector, like this:
http://www.kenable.co.uk/images/k-pcie-molex_main.jpg

I'm saying *Don't* use the single MOLEX to 6 Pin PCIE. It doesn't provide enough wattage on its own, and there have been a few people who've burned out the port using them. Get another 2x Molex to 6+2 pin PCIE (the one with the optional 2 that can be peeled back), or get an 2x Molex to 6 pin connector.

If you're getting a new power supply, it will have its own 6+2 pin PCIE connections, so this would be a non-issue in the case of you getting a newer PSU. But if you're considering testing with your 500W Seasonic at low-load, I would recommend getting a different molex to 6 pin adapter.
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March 19, 2014 2:47:43 PM

CraigN said:

I'm saying *Don't* use the single MOLEX to 6 Pin PCIE. It doesn't provide enough wattage on its own, and there have been a few people who've burned out the port using them. Get another 2x Molex to 6+2 pin PCIE (the one with the optional 2 that can be peeled back), or get an 2x Molex to 6 pin connector.



Craig,
Yes, those are the exact connectors, although in the case of the single 1x4pin molex to 6pin, the molex end of the 1x4 only actually uses 3 prongs/pins much like the molexes on your other image for the 2xpin molex to 8pin. But yes, those look just like the included cables.

So if I understand, you're saying that I would still use the 2x 4-pin Molex to 8-pin PCIE connector. But for the 6pin input on the mobo, I should instead use a 2x Molex to 6+2 pin PCIE. So that would mean I wouldn't actually use the +2 part because it would have no where to go, right? (thanks for the images, BTW... I tried to find some but links were a 1/2 page long. lol)

And if I can't get my hands on a 2x Molex to 6+2 pin PCIE cable, then you're saying it's probably not safe to power my build even on a low load for testing purposes, right? (Kind of a bad move on Sapphire's part shipping underpowered connectors).

I'm familiar with bus bars on a home electrical panel and I'm guessing that's what you're getting at with this talk of PSU rails. I'm guessing when I finally get my new PSU I'll need to be aware of this when powering the vid card? Will I need to make sure the vid card is powered from both rails to get adequate power? In other words, it won't be enough to have 4 molex connectors supply power. I'll need to make sure they are coming from both rails?
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Best solution

a b ) Power supply
March 20, 2014 5:12:52 AM

For low load, it would likely work, because your video card won't draw that much current on low load, but I would not recommend any stress testing in that setup. I wouldn't hook up my Titan using one of those, but that's just me. I'm very surprised to see that it was shipped with one of those, to be honest. I can't remember the last card I bought that provided a single Molex to PCIE connector. Probably my six year old GeForce 9600 GT.

The huge benefit of getting a new PSU is that most new 80+ rated power supplies will have their own dedicated PCI-Express power connectors, so you won't have to use the provided molex connectors at all.

A lot of the popular 550-650W PSUs I've seen/used only have one +12V rail. My own Corsair HX850 850W psu has only one +12V rail, so I don't think you'll need to go through that particular trouble with a new power supply if you find one with a single 12V rail.
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March 20, 2014 5:58:40 AM

Quote:
For low load, it would likely work, because your video card won't draw that much current on low load, but I would not recommend any stress testing in that setup. I wouldn't hook up my Titan using one of those, but that's just me. I'm very surprised to see that it was shipped with one of those, to be honest. I can't remember the last card I bought that provided a single Molex to PCIE connector. Probably my six year old GeForce 9600 GT.


I'm surprised too, but even the website specs on the card refers to the 1x6pin.

Quote:

The huge benefit of getting a new PSU is that most new 80+ rated power supplies will have their own dedicated PCI-Express power connectors, so you won't have to use the provided molex connectors at all.


Ah, good.

Quote:

A lot of the popular 550-650W PSUs I've seen/used only have one +12V rail. My own Corsair HX850 850W psu has only one +12V rail, so I don't think you'll need to go through that particular trouble with a new power supply if you find one with a single 12V rail.


Also good. I really appreciate you taking the time to explain this and help me think about it, but my plan is to forget about the S12 idea and just by a new PSU later today even if I can't find one on sale. I'll probably get it early next week and that still gives me time to check the components before the return policy runs out.

I checked the link you gave me where 550 is recommended for the R9 290. Anandtech show that the factory OCed R9 290 I bought does draw a little more power. At load it's pulling 413 vs. 384 for the stock. Do you think I'll be safe with 550 total watts?
http://www.anandtech.com/show/7601/sapphire-radeon-r9-2...

Edit: I hope you don't take this wrong, but I might repost this question specifically about whether or not the 550 is enough power in hopes of getting more responses. I'm a little worried about it.
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a b ) Power supply
March 20, 2014 6:34:29 AM

I wouldn't take it wrong. 413W is only 75% of the power of a 550W PSU, also, if you note on the graph, it says "Total System Power Consumption." The Tri-X is not pulling 413W on it's own. That would be insane. If you want to give yourself "safe" room, 600 or 650W would be the ideal without overspending, and leaving youself a good amount of headroom, but 75% of your max PSU power is fine. Especially considering, unless you're crypto-mining, you will only be at full power for a few hours whenever you're doing your work load heavy tasks, then idle the rest of the time. A decent PSU can handle being at 75% capacity for a few hours every day more than fine.

I personally believe (and haven't had any failures other than age or cheap PSUs by practicing this) anywhere between 50-80% load is a safe operating point for your PSU, but what you don't want to do is run at 90-100% of your PSU's max wattage all the time on your power supply when you're hardware is working at full power. For a few hours is OK, but if you're going to be Crypto mining or something like that, I'd get a stronger PSU.

I was more than happy to help, I hope all this information has been helpful for you :) 

[Quick Edit: I ran your build on PCPartPicker, and it only lists the TDP of the Tri-X at 250W by itself probably a little higher though, and your system came out to 433W max power total. A 600W would give yourself plenty of headroom, but you shouldn't be drawing that much power usually. The 384W would be accurate, as FurMark is a stress test, and generally unrealistic that your GPU will ever actually be operating in that condition]

Edit 2: I've made some edits to this post, so, refresh before you reply :p  lol
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March 20, 2014 7:03:18 AM

CraigN said:
I wouldn't take it wrong. 413W is only 75% of the power of a 550W PSU, also, if you note on the graph, it says "Total System Power Consumption." The Tri-X is not pulling 413W on it's own. That would be insane. If you want to give yourself "safe" room, 600 or 650W would be the ideal without overspending, and leaving youself a good amount of headroom, but 75% of your max PSU power is fine. Especially considering, unless you're crypto-mining, you will only be at full power for a few hours whenever you're doing your work load heavy tasks, then idle the rest of the time. A decent PSU can handle being at 75% capacity for a few hours every day more than fine.

I personally believe (and haven't had any failures other than age or cheap PSUs by practicing this) anywhere between 50-80% load is a safe operating point for your PSU, but what you don't want to do is run at 90-100% of your PSU's max wattage all the time on your power supply when you're hardware is working at full power. For a few hours is OK, but if you're going to be Crypto mining or something like that, I'd get a stronger PSU.

I was more than happy to help, I hope all this information has been helpful for you :) 

[Quick Edit: I ran your build on PCPartPicker, and it only lists the TDP of the Tri-X at 250W by itself probably a little higher though, and your system came out to 433W max power total. A 600W would give yourself plenty of headroom, but you shouldn't be drawing that much power usually. The 384W would be accurate, as FurMark is a stress test, and generally unrealistic that your GPU will ever actually be operating in that condition]

Edit 2: I've made some edits to this post, so, refresh before you reply :p  lol


Thanks a lot Craig. Sorry I missed the "Total System Power Consumption" qualifier at Anandtech. I'll never do crypto-mining, but I do try to create a quality build and often I pass down my old PCs to family members so I do want it to last.

Regarding your quick edit, the stock R9 290 was the 384 while the tri-x I own came in at 413. I didn't realize I could use PCPartsPicker for assessing power usage. Thanks for that tip as well. I'll need to think about it a bit.

Thanks for all your help.

Edit: I'm showing 508W on PPP:
http://pcpartpicker.com/p/3daHP
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a b ) Power supply
March 20, 2014 8:52:59 AM

Muckster said:

Thanks a lot Craig. Sorry I missed the "Total System Power Consumption" qualifier at Anandtech. I'll never do crypto-mining, but I do try to create a quality build and often I pass down my old PCs to family members so I do want it to last.

Regarding your quick edit, the stock R9 290 was the 384 while the tri-x I own came in at 413. I didn't realize I could use PCPartsPicker for assessing power usage. Thanks for that tip as well. I'll need to think about it a bit.

Thanks for all your help.

Edit: I'm showing 508W on PPP:
http://pcpartpicker.com/p/3daHP


On the Furmark, yes, 384 was the stock 290. On Crysis 3, it was 384 on the Tri-X, which I believe to be a far more realistic expectation of how much (max) power you'll actually be drawing. As I mentioned, Furmark is purely a stress-test, and the temperatures and power consumption you get in that test is an unrealistic expectation to what your normal use would consist of.

PCPartpicker estimates the max possible draw, so that's why 500W might seem high. Also, I only did the GPU, CPU, SSD, and CPU cooler to get a rough idea on your build, so missing the extra fan and hard drive drive would account for my lower #.

I think you could get by fine with a (good) 550W PSU, but it couldn't hurt to go with an 80+ Gold 600W.
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March 20, 2014 9:12:10 AM

Cool. Thanks again Craig.
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