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Is 650W enough

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Last response: in Components
August 25, 2009 8:24:06 AM

Is 650 Watts enough for all of this???


CPU: AMD Phenom II X3 720 2.8GHz Socket AM3 95W Triple-Core Black Processor Model HDZ720WFGIBOX - Retail

HDD: Western Digital Caviar Black WD6401AALS 640GB 7200 RPM SATA 3.0Gb/s 3.5" Internal Hard Drive - OEM

Mobo: BIOSTAR TForce TA790GX A3+ AM3 AMD 790GX HDMI ATX AMD Motherboard - Retail

GPU(s): HIS H489FT1GP Radeon HD 4890 1GB 256-bit GDDR5 PCI Express 2.0 x16 HDCP Ready CrossFire Supported Video Card - Turbo OC Edition - Retail (Two of them)

Case/PSU:Antec Nine Hundred + EA650 Black Steel ATX Mid Tower Computer Case 650W Power Supply - Retail

CD/DVD Burner: LG Black 22X (CAV) DVD+R 8X DVD+RW 16X DVD+R DL 22X (CAV) DVD-R 6X DVD-RW 12X DVD-RAM 16X DVD-ROM 48X CD-R 32X CD-RW 48X CD-ROM 2MB Cache SATA 22X DVD±R DVD Burner with LightScribe LightScribe Support - OEM

RAM/Memory: Patriot Gamer Series 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model PGS34G1600ELKA - Retail

Monitor: ASUS VH226H Black 21.5" 2ms(GTG) HDMI Widescreen LCD Monitor - Retail **Item #: N82E16824236051

Card Reader: SABRENT CRW-UINB 68-in-1 USB 2.0 Internal Card Reader w/ USB 2.0 Port supports SDHC/VISTA - Retail **Item #: N82E16820300608

More about : 650w

a b ) Power supply
August 25, 2009 8:35:46 AM

^ Actually a 650W PSU can power that rig but it is highly not advisable...
A 700W PSU would be better but will not have much headroom left...
A 750W PSU would be a very safe and good choice... and can even handle a good overclock...
a b ) Power supply
August 25, 2009 8:36:45 AM

Corsair 750TX would be the best pick...
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August 25, 2009 8:49:06 AM

Highly not advisable? That rig will use 450-500W, tops. A good quality 650 would easily power all of that. That Antec isn't amazing, but it will get the job done if you're strapped for cash.

If you plan on future upgrades however, and can afford a different PSU, I'd get a Corsair 750TX. Even if you don't plan on future upgrades, I'd recommend a different PSU, such as a Corsair TX650, Antec Signature 650 (awesome PSU, but REALLY pricey for a 650), or the Seasonic M12 700W, to name a few of the higher end ones.
August 25, 2009 8:51:00 AM

The case I am getting comes with the 650W PSU.

So I should purchase another PSU to put in place of that one???
August 25, 2009 9:12:25 AM

@cjl: the OP will run 2 4890s.

Can't you buy the case and the PSU separately? Buy the case w/o PSU then buy a tx750.
August 25, 2009 9:21:01 AM

Yep. A pair of 4890s will only take 450-500W, tops. Most people overestimate power usage.
August 25, 2009 9:21:59 AM

Use it on your own risk. I have china made stock PSU blow on me before that take out the Mainboard, CPU and Ram with it.
August 25, 2009 9:24:16 AM

I have the Corsair 650TX, awesome PSU. I'm sure it will have enough juice to power my second (future) 4870. Your 650 should be fine too.

Check out the PSU Calculator here:
http://extreme.outervision.com/psucalculatorlite.jsp

When upgrading, have a look here:
http://www.xtremesystems.org/forums/showthread.php?t=10...

What I would like to know is: If I read on the net about similar rigs drawing around 550W from the wall socket, will my 650 be ok? How close can one safely get to the PSU's rating?
August 25, 2009 9:27:26 AM

550 from the wall socket is nowhere near the limit of a 650W PSU. PSUs are rated for DC output, not AC input, and at 84% efficiency, that 550 from the wall is only 462 watts of actual output (leaving an extra 188 watts of headroom in a 650W PSU).
August 25, 2009 9:40:06 AM

There was an article based on power consumption on Tom's. I hardly advise to read that one before posting replyes http://www.tomshardware.com/reviews/geforce-radeon-powe....

You will see that not only the Watts are important, the Amps on the +12V line also.

@cjl: You are wrong. Every PSU will deliver the Watts but it will consume more power from the plug. So if a PSU has 500W with an efficenty of 85%, it will deliver you the 500W but therefore consume 15% more energy to do that (this will only affect you bill).
August 25, 2009 9:49:13 AM

cjl said:
550 from the wall socket is nowhere near the limit of a 650W PSU. PSUs are rated for DC output, not AC input, and at 84% efficiency, that 550 from the wall is only 462 watts of actual output.


It should take ~655W from the wall if it consumes 550W at 84% efficiency, not 462W. Most people underestimate power usage that's why they encounter performance problems afterward. Plus total wattage isn't the case here. What matters is the 12v rail wattage and that's what you should look at.
August 25, 2009 9:57:10 AM

The Antec EA650 has 45A accross 3 X 12V rails. I believe this to be less desirable than the 52A single rail on the Corsair 650TX?
August 25, 2009 10:03:34 AM

It is better but still, a tx750 should be used if your doing CF/SLI setups as you still have other components other than the video card that needs power. Especially when the CPU is OCed. Some people would even recommend a tx850 as a safe ground.
a c 195 ) Power supply
August 25, 2009 10:09:20 AM

The SG-650 is a great PSU, but for some reason only has two PCIE power connectors; a 6-pin and a 6+2 pin.
A Truepower New 750W PSU is 80+ bronze, has four connectors, is semi-modular, and reviews a little better than the Corsair or PC Power & Cooling (www.jonnyguru.com)
a c 195 ) Power supply
August 25, 2009 10:14:04 AM

Btw, if you go here: http://game.amd.com/us-en/crossfire_certified.aspx?cat=... you'll see that ATI certifies the Earthwatts 650W PSU for a pair of 4890s in Crossfire. The Earthwatts is another PSU that consistently reviews well. The SG-650 is there too, of course, but you'd need to use adapters.
a b ) Power supply
August 25, 2009 10:27:05 AM

@cjl I would have to agree with you...

After checking out the ATI website PROPERLY(which I have never done before), I saw this info...

"*500 Watt or greater power supply with two 75W 6-pin PCI Express® power connectors recommended (600 Watt and four 6-pin connectors for ATI CrossFireX™ technology in dual mode) "
Source - http://www.amd.com/us/products/desktop/graphics/ati-rad...

That can power 2x HD4890s (Toms had a review of the Cyberpower Dragon PC which had an overclocked X4 955 + 2x HD 4890s powered by Corsair 650TX)

But also in the review it was pointed out that having some headroom is better as the power could peak higher and we know that the PSUs would deteriorate with usage...

So 650W would be fine, But the Corsair or the Antec Sig that jtt283 suggested would be a better option than the EA...
a c 244 ) Power supply
August 25, 2009 11:10:15 AM

gek77 said:


@cjl: You are wrong. Every PSU will deliver the Watts but it will consume more power from the plug. So if a PSU has 500W with an efficenty of 85%, it will deliver you the 500W but therefore consume 15% more energy to do that (this will only affect you bill).

You really should reread his post.
August 25, 2009 12:29:35 PM

Sorry, I didn't open the link and I understood this wrong. I thought "cjl" has done the math bakwards.
a c 195 ) Power supply
August 25, 2009 12:41:37 PM

If it were me, I would trust the EA for this rig; no need to replace if it is part of a deal. If it isn't, or you find a different deal, then I'd go for the Truepower New (or SG).
a b ) Power supply
August 25, 2009 2:20:22 PM

masterjaw said:
It should take ~655W from the wall if it consumes 550W at 84% efficiency, not 462W.

That was 550 at the wall, not 550 DC.

Quote:
Most people underestimate power usage that's why they encounter performance problems afterward.

Most people grossly overestimate the power they need, but many of them get poor quality PSUs.
August 25, 2009 8:57:37 PM

masterjaw said:
Most people underestimate power usage that's why they encounter performance problems afterward. Plus total wattage isn't the case here. What matters is the 12v rail wattage and that's what you should look at.

Most people vastly overestimate power usage, which is why you see so many posts asking whether 750 or 1000 watts is needed for an athlon x2 and a GTX 275. However, they try to go cheap on their PSUs, and a cheap "750" is far, far worse than a good 500-600W will ever be. Get a good quality PSU, and you don't actually need that much for most systems.
a b ) Power supply
August 25, 2009 9:06:52 PM

2 4890's under load draws 465 watts on their own under load at stock speeds
August 25, 2009 10:36:12 PM

obsidian86 said:
2 4890's under load draws 465 watts on their own under load at stock speeds


Measured how? By who? It's very difficult to isolate one set of parts of a system, which is why most good reviews report on total system usage. One could extrapolate, I suppose, by measuring total system draw of a system with one GPU then adding another GPU and measuring that system draw, then making the supposition that the difference is the draw for one GPU....
August 25, 2009 11:01:10 PM

i agree with cjl, a 650w would be plenty

650w@84% eff would give you 774w at the wall
a b ) Power supply
August 26, 2009 5:52:37 AM

obsidian86 said:
2 4890's under load draws 465 watts on their own under load at stock speeds

That would require a lot of voltage which would more than likely kill the cards instantly.
August 26, 2009 4:45:10 PM

650W power supply will be fine when the power supply is BRAND NEW. Be aware of aging capacitors. When they begin to age, your output DC power will go down significantly. I'd cough up the extra green for 750W for that rig.
August 26, 2009 4:48:28 PM

theAnimal said:
That would require a lot of voltage which would more than likely kill the cards instantly.


don't post comments if you don't know what you're talking about. Wattage = Voltage * Amperage. The 12V rail on a good power supply should have a constant 12V under load as well as when in idle. That is the difference in a good supply and a cheap one.
a b ) Power supply
August 27, 2009 6:33:08 AM

sepayne21 said:
don't post comments if you don't know what you're talking about.

Excellent advice; I'd recommend following it.

2 HD4890s will draw nowhere near 465W (more like 265W), so in order for them to reach that power usage they would need to be volt modded to a level that would very likely mean instant death.
August 27, 2009 11:48:09 AM

theAnimal said:
Excellent advice; I'd recommend following it.

2 HD4890s will draw nowhere near 465W (more like 265W), so in order for them to reach that power usage they would need to be volt modded to a level that would very likely mean instant death.


I stated in my previous post, Wattage = Voltage * Amperage. you're correct that If you up the voltage you're increasing the power consumption, but my point isn't that the supply won't work when it is BRAND NEW... it will work when it's brand new. Capacitors age, and when they do, your 12V rail will suffer greatly from that. This is why manufacturers recommend huge power supplies.

I stand by my original post. 650W will work, but I'd recommend 750W b/c of aging capacitors.

One more reason to buy the 750W has to do with all of the fans (motors) on your board. Startup current for motors have a current draw of 6 X full load current. so, you can expect a larger power draw when the fans go from low speed to high speed when you put full load on your sys while gaming than the steady state full load of the system. Steady state Full load will be lower than the transient to full load (system will be at full load, but fans will be ramping up to achieve rated speed).
a b ) Power supply
August 27, 2009 4:11:06 PM

sepayne21 said:
I stated in my previous post, Wattage = Voltage * Amperage. you're correct that If you up the voltage you're increasing the power consumption, but my point isn't that the supply won't work when it is BRAND NEW... it will work when it's brand new. Capacitors age, and when they do, your 12V rail will suffer greatly from that.

I was not talking about the PSU at all; you cannot up the voltage on a PSU. The voltage of the video card is not related to the 12V rail of the PSU. In order for an HD4890 to draw 232.5W, you would have to increase the voltage on the card significantly (you cannot increase the amps). Overvolting the card by the large amount necessary would kill it.

Example: HD4890 @ 1.25V uses 125W, in order to increase to 232.5W, you would need to nearly double the voltage.

Quote:
This is why manufacturers recommend huge power supplies.

They recommend this due to the number of crappy PSUs which are available.

Quote:
One more reason to buy the 750W has to do with all of the fans (motors) on your board. Startup current for motors have a current draw of 6 X full load current. so, you can expect a larger power draw when the fans go from low speed to high speed when you put full load on your sys while gaming than the steady state full load of the system. Steady state Full load will be lower than the transient to full load (system will be at full load, but fans will be ramping up to achieve rated speed).

Since the CPU and GPU(s) are not stressed at startup, the extra power draw of a fan that only uses 1-2W makes almost no difference (unless you have a very large number of them).
August 28, 2009 1:30:44 PM

I'm not talking about startup. I'm talking about when your GPU is hits load, your temps rise which causes the fans to go from a low speed to a high speed. This is your transient to full load (and when your sys will be taxed the most). Once your fans are at rated speed, this is steady state full load and it will be slightly less than your transient to full load.

if you have 2 gpu's that have fans that pull about 5 watts full load, when you ramp them up from idle, they're probably drawing 10-15 watts (times 2 cards + cpu fan). Granted, this is not much, but the extra draw is there.

also, you're wrong about doubleing the voltage (at the video card) will double your power consumption. the Voltage/current curve on transistors are nonlinear (even if they were, to double your power, you'd have to increase your voltage by a factor of sqrt(2)). As you increase voltage, your current consumption will increase as well.

All of the above are minor details (however, they do add up) but the main point is the aging capacitors. If you place the same burden on a 750W vs a 650W, the 750 lifespan will be much longer (usually due to the aging capacitors).

Like I said before, the 650W will work NEW, but you have to take into consideration aging capacitors.