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Is 500Watts enough?

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April 10, 2010 10:23:25 PM

Here is my build list:


MOBO: http://www.newegg.com/Product/Product.aspx?Item=N82E168...

CPU: Intel i5-750 http://www.newegg.com/Product/Product.aspx?Item=N82E168...

GPU: Diamond Radeon HD4650 1GB DDR3

RAM: G.SKILL Ripjaws 2x2GB 1600

HDD: WD 640GB Caviar Black (maybe a SSD in the future)

2 CD drives: 1xDVD, CD ROM 1x DVD/CD burner

Other: Maximum of 6 case fans, Fan controller(possibly lcd), card reader, and maybe a few occasional usb devices, and a TV tuner.


I used this PSU calculator http://www.extreme.outervision.com/psucalculator.jsp and got something like a minimum of <250W ? That maybe rethink my previous choice of an Antec Earthwatts 650 and bring it down to the 500W version. Really the only things subject to change in the future is I may get a better GPU but it would still be a single(no sli), and possibly another HDD or SSD.


Any suggestions? (preferably under $100)

More about : 500watts

April 10, 2010 10:32:41 PM

That setup looks pretty spiffy, but I might make a few suggestions.

500 watts will *probably* be enough... for now. I'd recommend future-proofing and going back to the 650-watt PSU as a minimum in case your priorities change in the future. It would truly be painful to have to buy a new PSU because you bought one too weak for later upgrades. I myself prefer the Silverstone SST-ST70F. If you can find a sale within your price range, go for it. Rock solid unit.

If this is for a gaming rig, the 4650 will be a bit on the light side. I'd recommend nothing less than a 5770 in that case.

P.S. - 250 watts is a nonsensically low estimate. Disregard it completely.
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a b ) Power supply
April 10, 2010 10:35:46 PM

The 4650 is a fairly miserly card with repect to power. If you plan on upgrading to a more powerful card in the future I would go with the 650.

As is though, the 500w is enough.
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a b ) Power supply
April 10, 2010 10:54:46 PM

As your system sits a 300 watt PSU will power it with no problem. A quality 500 to 550 watt PSU will run any single GPU with the exception of the HD5970 and GTX480 besides those 2 cards 550 watt is all you will ever need as long as its a quality PSU. The reason all them manufactures inflate their power requirements is that they know that there are tons of cheapo PSU around. A good Corsair or Antec 550 watt will be more then enough to give you headroom for upgrade.
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April 10, 2010 11:26:17 PM

Thanks for the responses guys. It is very intimidating seeing the vast number of power supply manufacturers not to mention the power ranges. So since a 550W power supply will easily power my system I may as well spend that extra $10 and get 100watts more to keep from having any problems with upgrades I may randomly decides to make in the future, just to take the guess work out of it.
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a c 144 ) Power supply
April 10, 2010 11:30:12 PM

AMD recommends at minimum a 400W unit:
http://www.amd.com/us/products/desktop/graphics/ati-rad...

If you think you might get a stronger graphics card, then a simple rule is to buy a quality psu with enough 6 or6/8 pin pcie leads go connect up your graphics configuration without adapters.

A psu is the last place to economize, previous posters have made some good suggestions.
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April 11, 2010 6:11:01 AM

geofelt said:
AMD recommends at minimum a 400W unit:
http://www.amd.com/us/products/desktop/graphics/ati-rad...

If you think you might get a stronger graphics card, then a simple rule is to buy a quality psu with enough 6 or6/8 pin pcie leads go connect up your graphics configuration without adapters.

A psu is the last place to economize, previous posters have made some good suggestions.



I know...it said 400W power supply required on the box :ange:  .

And I'm using a 430W Thermaltake TR2 PSU for it right now on a nothing special PC.
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Best solution

April 11, 2010 8:33:24 PM

mushroomking said:
Thanks for the responses guys. It is very intimidating seeing the vast number of power supply manufacturers not to mention the power ranges. So since a 550W power supply will easily power my system I may as well spend that extra $10 and get 100watts more to keep from having any problems with upgrades I may randomly decides to make in the future, just to take the guess work out of it.

550W is already more than you need. If you're not going to CF/SLI with the higher end cards you don't need to go higher. I have a similar build, the biggest difference being I have the i7 860. With Intel's SpeedStep enabled my rig spends most of its life sucking up 75W, even when loaded fully under Prime95 I've never seen it hit 190W.

You might be interested in this article, it's a little dated but still relevant: http://www.anandtech.com/show/2624/1

Off topic, wanted to make sure you knew you wouldn't be able to run your RAM at 1600 MHz unless you OC your rig or make other trade-offs. Even if you don't OC, it can still be great RAM to get for your system and running at 1333MHz is not that different from 1600MHz in most real world applications, I just wanted to make sure you knew that in advance so you weren't surprised or upset by it later.
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April 11, 2010 11:56:41 PM

ekoostik said:
550W is already more than you need. If you're not going to CF/SLI with the higher end cards you don't need to go higher. I have a similar build, the biggest difference being I have the i7 860. With Intel's SpeedStep enabled my rig spends most of its life sucking up 75W, even when loaded fully under Prime95 I've never seen it hit 190W.

You might be interested in this article, it's a little dated but still relevant: http://www.anandtech.com/show/2624/1

Off topic, wanted to make sure you knew you wouldn't be able to run your RAM at 1600 MHz unless you OC your rig or make other trade-offs. Even if you don't OC, it can still be great RAM to get for your system and running at 1333MHz is not that different from 1600MHz in most real world applications, I just wanted to make sure you knew that in advance so you weren't surprised or upset by it later.



I'm glad you mentioned it but it says I can use 1600/1333/1066 without overclocking, 2200 with overclocking. So off that just curious what makes you think I cant use the 1600?
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a c 144 ) Power supply
April 12, 2010 12:15:14 AM

1600 ram is better binned normal 1.5v ram that can operate at 1600 with 1.65 volts. Of course you can use it. Realize though that the value of ram speed is quite overrated, particularly with i3/i5/i7 cpu's which have excellent memory controllers. The difference in real application performance or FPS might be 1-2%. Not much of a return for any extra cost or effort to me.
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April 12, 2010 12:51:06 AM

geofelt said:
1600 ram is better binned normal 1.5v ram that can operate at 1600 with 1.65 volts.

This isn't always true, sometimes you can do better than that! For exaple, the 1600 GSkills I have run at 1.5V.

mushroomking said:
I'm glad you mentioned it but it says I can use 1600/1333/1066 without overclocking, 2200 with overclocking. So off that just curious what makes you think I cant use the 1600?

Before I launch into a detailed explanation let me say a couple things. First, if you haven't read this review yet you should give it a read, it compares different memory speeds and is very informative, especially the conclusions (but if you jump to the end you'll miss some of the meat): http://www.tomshardware.com/reviews/core-i7-870-1156,24...

Second, even if you don't plan on OCing, there can still be very good reasons to get 1600 MHz RAM. One of the best reasons - sometimes its cheaper than similar 1333 MHz RAM. Sometimes 1600 RAM can be run at 1333 with tighter timings. Sometimes it can be run with lower V when set to 1333. 1600 RAM is nothing but 1333 RAM that the manufacturer certifies as OCable. I kinda like the way this article on value RAM puts it:
Quote:
Performance guarantees are nice, but paying someone else to validate an overclock can put a big dent in the value a mid-priced system represents. After all, most builders don't pay extra for a CPU that has been validated by a third party to run at higher speeds, yet very few overclocking enthusiasts seek better value by risking the chance of a “poor yield” in exchange for a lower price. We willingly take that small risk with processors, so why not apply the same principle to RAM?


Now for the answer to your question: What makes [me] think that [you] can't use the 1600?

A: You can use the 1600. You just can't run it at 1600 without OCing or making other tradeoffs.

With an i5 750 you cannot run RAM any faster than 1333 with effectively OCing your computer. You can often turn on XMP in BIOS, and many people recommend doing this, but this changes your BCLK which also affects your CPU speed. It might, as a side effect, end up turning off functionality such as Turbo, EIST, sleep states. You can usually turn those back on but you have to specifically do it. This differs from motherboard to motherboard.

To provide more detail on why memory multipliers and XMP affect your CPU, we need to discuss how the RAM and CPU speeds are determined. There are 3 important settings: BCLK, Memory Multiplier, and the CPU Clock Ratio.

RAM Speed = BCLK x Memory Multiplier
CPU Speed = BCLK x CPU Clock Ratio

By default, the 1156 socket chips run with a BCLK of 133. The CPU and RAM attain different speeds by using different multipliers.

The Max Memory Multiplier that is available to the i5 750 chip (and the i5 and i3 Clarkdale chips) is one that allows RAM to reach a speed of 1333 MHz at default BCLK. Doing the math, this is basically 10 (some boards treat it differently, but fundamentally it can be thought of as 10) because 133 BCLK x 10 Memory Multiplier = 1333 MHz. This is the max frequency RAM can run at with the i5 750 without OCing.

The Max Memory Multiplier that is available to the i7 8xx chips is one that allows RAM to reach a speed of 1600 MHz at default BCLK. Doing the math, this is essentially 12 because 133 BCLK x 12 Memory Multiplier = 1600 MHz.

The i5 750 runs with a default CPU Clock Ratio of 20. This gives it it's default CPU speed of 133 BCLK x 20 CPU Clock Ratio = 2.66 GHz. When XMP is turned on for 1600 MHz RAM, the BCLK is usually changed to 160 (this could differ between boards as well, but in my experience and what's been reported the BCLK changes to 160). Remember, the max memory multiplier available to the i5 750 is 10, so to hit 1600 MHz the motherboard must change the BCLK to: 1600 / 10 = 160.

As a result of this BCLK change, the CPU speed changes. If the CPU Clock Ratio did not change your CPU would be OCed to 20 x 160 = 3.2 GHz. Most (if not all) motherboards would deem this too dangerous to allow when all a user does is enable the XMP profile. So, the boards drop the CPU Clock Ratio in response to the raised BCLK. Based on what I've seen around the forum, most (all?) boards will drop the CPU Clock Ratio to 17. This means your CPU is running at a speed of 17 * 160 = 2.72 GHz.

Gigabyte treats this as an OC and from what I've been told around this forum other motherboards do the same. If you have left other settings as is, the motherboard will disable Turbo, EIST, and Sleep States. This is the trade-offs I've been talking about. These functions can be turned back on, but you have to go in and flip the settings from "Auto" to "Enabled" (the setting may differ for Asus). "Auto" means the motherboard decides whether or not to allow these functions. By setting it to "enabled" you ensure that they are always available. Furthermore, if you want to keep Turbo you have to change your CPU clock ratio back up to 20.

Of course once you have XMP turned on and your BLCK gets bumped up to 160, Turbo will run your machine even faster. When Turbo kicks in, the CPU Clock Ratio changes. For example, with one core of an i5 750 active Turbo might raise the CPU Clock Ratio as high 24. This gives a stock CPU a max speed of 133 BCLK x 24 CPU Clock Ratio = 3.20 GHz. But with XMP on and a BCLK of 160, your new max speed is 160 x 24 = 3.84 GHz. You'll want to test your system for stability running at these settings. Keep an eye on Voltage and heat.


Putting this all together, at default/stock we have:
BCLK = 133
Memory Multiplier (effectively) = 10
CPU Clock Ratio = 20

RAM Speed = BCLK x Memory Multiplier = 133 x 10 = 1333 MHz
CPU Speed = BCLK x CPU Clock Ratio = 133 x 20 = 2.66 GHz

When Turbo kicks in (for example, let's say it is at it's max):
BCLK = 133
Memory Multiplier (effectively) = 10
CPU Clock Ratio = 24

RAM Speed = BCLK x Memory Multiplier = 133 x 10 = 1333 MHz
CPU Speed = BCLK x CPU Clock Ratio = 133 x 24 = 3.20 GHz


With 1600 RAM and XMP on
BCLK = 160
Memory Multiplier (effectively) = 10
CPU Clock Ratio = 17

RAM Speed = BCLK x Memory Multiplier = 160 x 10 = 1600 MHz
CPU Speed = BCLK x CPU Clock Ratio = 160 x 17 = 2.72 GHz

With 1600 RAM and XMP on, when Turbo kicks in, assuming you turn it back on and OC your rig by raising your cpu clock ratio back to 20:
BCLK = 160
Memory Multiplier (effectively) = 10
CPU Clock Ratio = 24

RAM Speed = BCLK x Memory Multiplier = 160 x 10 = 1600 MHz
CPU Speed = BCLK x CPU Clock Ratio = 160 x 24 = 3.84 GHz
As I said before, you're overclocking now and you'll want to test your system for stability running at these settings. Keep an eye on Voltage and heat. Also, although I used XMP as an example you could accomplish the same thing by setting BCLK, the memory multiplier, timings and voltage by hand.
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April 13, 2010 4:44:13 PM

Thanks for writing all of that ekoostik! There were a few things in there I had to look up :ange:  . But that was very informative and filled in a lot of the the grey area for me. So basically If I dont plan to overclock the system to 3.2gHz+ I should just go for the 1333 and save possibly a bit of headache, even though both speeds are relatively the same price.
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a c 144 ) Power supply
April 13, 2010 7:34:09 PM

mushroomking said:
Thanks for writing all of that ekoostik! There were a few things in there I had to look up :ange:  . But that was very informative and filled in a lot of the the grey area for me. So basically If I dont plan to overclock the system to 3.2gHz+ I should just go for the 1333 and save possibly a bit of headache, even though both speeds are relatively the same price.


If you do not pay much of a premium, why not get the 1600ram?
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a c 144 ) Power supply
April 14, 2010 1:10:02 AM

mushroomking said:
I cant say absolutely for sure but I figured the 1333 of the same price with better timings and lower voltage was the way to go especially since I wouldn't be overclocking. Here are the links to the two I'm between:

1333: http://www.newegg.com/Product/Product.aspx?Item=N82E168...

1600: http://www.newegg.com/Product/Product.aspx?Item=N82E168...


Since the price is almost the same, get the 1600 ram. It gets it's speed from a higher voltage of 1.65.

It will operate just fine at 1.5v. I think the better quality chips will go into the faster ram. The slower ram may not be capable of going faster easily.

In the end, it does not make a significant difference to your application performance or FPS. Think 1-3%.
Don't anguish over the choice.
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April 14, 2010 2:12:44 AM

Agreed. You can't go wrong with either one. The timings are close enough that you won't notice the difference. And there's a good chance that you could run the 1600 rated RAM at 1333 MHz using the same timings and the same 1.5V as the 1333 rated RAM. If you don't want to mess with BIOS settings then save yourself the $5 and get the 1333 RAM. But if you want to learn about your BIOS settings and do a little tweaking in there or if you want to leave yourself some extra headroom for possible OCs later get the 1600s and just run them at 1333 for now. In my estimation, the decision comes down to the $5 difference and your appetite for tweaking with the motherboard settings. As geofelt said, don't agonize over it. Pick whichever one feels right to you and you'll be happy.
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April 14, 2010 3:55:19 AM

Well maybe I'll just go for the 1600 and make this a learning experience. Thanks for the help guys much appreciated. I just hope once everything is together and I push the power button that it actually starts ;)  .
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April 14, 2010 12:14:51 PM

Good luck, and have fun with it!
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April 21, 2010 1:25:17 AM

ekoostik said:
Good luck, and have fun with it!



Everything worked out fine I got the 1600 and it started right up. Pretty much everything in my bios had auto setting but just to say I did I manually turned the ram speed to 1333. And I got the Antec BP-550W power supply.
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April 21, 2010 1:26:21 AM

Best answer selected by mushroomking.
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April 21, 2010 2:23:27 AM

mushroomking said:
Everything worked out fine I got the 1600 and it started right up. Pretty much everything in my bios had auto setting but just to say I did I manually turned the ram speed to 1333. And I got the Antec BP-550W power supply.

Glad to hear everything went smoothly. Thanks for reporting back. Enjoy your rig!
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