AMD and DDR3

[Hijacker]

So I'm doing some research on what I want in my next build. I'm a huge AMD fanboi. Have been for years, and always will be. I feel ashamed that I spent 5 minutes contemplating using an Intel platform a few months ago.

Anyways, the board I'm looking at using is the Asus M3A79-T Deluxe. I was doing some research on the southbridge design as it's supposed to be superior to the old SB600 southbridge. In my research, I dug up this article from softpedia. My interpretation of it is that the boards with a 790FX northbridge and an SB750 southbridge will be AM3 compliant and have DDR3 support.

The M3A79-T utilizes that combination. If so, that makes me a very happy person because I can spring for 4 gigs of DDR3 memory instead of having to stay with DDR2. It's wishfull thinking, but when I see things like this Asus M3A78-T 790GX board that states it has DDR3 sideport, it makes me wonder. The 790GX is nothing more than a 790FX with integrated graphics on the PCB.

EDIT: I realize after the fact that the DDR listed on the latter mobo was memory for the integrated graphics chip. Bleg.

[Looneybomber]

I've been thinking that same thing.zer...r-am3

I have yet to find an AM2+ board with DDR3 support.What I have found though is a power supply that I like, so I bought it.http://www.newegg.com/Product/...94030

However, now I see newegg has the modular version of that same power supply on sale with an additional $80 MIR!http://www.newegg.com/Product/...94027

I would have much rather had that modular one, but I still got a heck of a deal on mine through an ebay store. $72 shipped, with sales tax.

Now I'm working on finding a computer case. I figure by the time I get most of my stuff bought, DDR3 AM2/AM3 boards will be out...hopefully.

[Hijacker]

I'm not too concerned with getting DDR3 boards right now. I've been running an old Athlon64 single core for so long, that upgrading to an AM2+ socket with 4 gigs of DDR2 1066 will be an amazing leap. Plus, the current price of the high end phenom is really low. I can pick up a 9950 BE for a really good price.

I was kind of hoping that the current AM2+ boards with the proper bridge combinations were already DDR3 compliant. After doing some more reading, it doesn't seem that way.

I'm still in the hunt for a case as well. I've been using an old old antec full tower and it's way past it's prime. Marenta's got a really snazzy CoolerMaster stacker I like, but after doing some power computations, I might have to go with a dual PSU setup for my end rig. And the only case I found that I like with dual PSU slots in it is this one. Marenta wants me to get it, but I was a bit kind of about it first, but knowing I'll need a dual PSU setup now, it seems a lot more enticing. Another case that has dual PSU spots in it, but I just don't like the unassuming look. If I'm going full tower, I want something with some penache.

[Looneybomber]

Dual PSU? Are you planning on quadfire (4 x-fire cards) and liquid cooling? Those cases look great, but the price is a bit steep for me. I do like the full tower cases, but for my use, a mid-tower is what I need.

Me I'm aiming for subtleness; quiet & conservative. An HTPC to also be used for some gaming. The problem I've run into is trying to find a small mid-tower that's also 8.5" wide to fit the 160mm tall CPU cooler I want.

I've been eyeballing Lian Li cases and they do make some dual PSU full-towers, but if you're wanting a little verve, look elsewhere.

[Hijacker]

I'll definitely be doing dual. Possibly tri-fire. My power consumption should be about 1,240W Factor in headroom and I'm at 1,860W. Granted, I'm doing max consumption for everything because I figure if I plan for the maximum load I can put on a system, then I'll be way over the mark and never be able to outdraw my supply.

I usually go the function over form route for case design. I'd rather have a case with good flow characteristics and look plain, than one that might look flashy but ends up burning up my mobo. I've fried 2 mobos now in my current antec full tower due to poor circulation. That was fixed with an extra puller fan in the front.

Years ago, it was either get flash with crap flow or get good flow with a plain jane look. I'm noticing a lot more stylistic designs now that offer good flow characteristics, so I'm gonna get one that looks nice and still gets the job done.

[Looneybomber]

Wow, maybe I'm underestimating how much power I'll be drawing. I was anticipating 350-400w while gaming and thus why I got a 625w PSU. I am only planning using a single 4870 w/512MB, dual HDD's, Phenom 9950, 4GB ram.

For function over form, I'd love to have a full tower again, but I just can't fit that big of a case, consequently the reduction of fans will reduce my air flow. This Lian Li mid-tower should work OK for me with dual 120's in the front and a single out back.http://www.tigerdirect.com/app...=1842Plus the more fans I have, the slow I can spin them to help reduce noise will still providing adequate cooling.

Lian Li's dual PSU full tower.http://www.tigerdirect.com/app...=1510

[Hijacker]

I go by PC Power & Cooling's consumption totals. They're usually on the ball and very accurate.

I anticipate:250W per vid card (2x to 3x)150W Mobo140W CPU (Phenom is DEFINITELY a 140W monster)15W per 1GB RAM (I'll be running 4 gigs)10W per PCI card (I anticipate Wi-Fi card and Sound card)30W for optical drive30W per HDD (I anticipate 2 HDDs)3W per fan. (I rounded up to 10 fans as that was the max on one of the cases I was looking at)Total: 1,240W

PC P&C say you should anticipate an extra 50% just for safety's sake and to give your PSU overhead. So that makes it 1,860. I figured I can run two 1kW PSUs and be fine with expansion room for a 4th card if I feel like I should go that route.

A 4th card is really only needed if I were to be running high resolution on a big monitor with all the features turned on. My current monitor's native resolution is somewhere around 1400x900.

Since I'm anticipating running 2 cards for the time being, I'll set up my dual PSU setup with my current 550W Antec unit and run it secondary to a 1350W Coolmax unit or a 1200W PC P&C unit. The Coolmax is topping my list right now due to cost per output.

[Looneybomber]

Those numbers may be a bit high, or at least the video card numbers.

From the latest video card review I saw on SilentPC, they tested the Asus ENGTX260, Nvidia GTX260 based card.Quote »The ENGTX260 is clearly the most power hungry card we've tested, using up to 122W DC on full load, topping the X1950XTX's 110W and HD 4850's 101W draws. Given these results, it's very impressive that the card can be cooled quietly by the stock cooling unit. At idle the card draws only 35W, which is actually fairly low for a high-end video accelerator, though more modest cards like the HD 3850/3870 use half that.[/quote]SilentPC built a computer and measured it to use 256w (95w idle). According to the P&C number's you gave, it would use ~663w.http://www.silentpcreview.com/article28-page4.html

With that in mind, you'd buy a 1000w PSU that'd put out 100-260w and thus operate at 50-60% efficiency. Or you could buy a 500w PSU that'd operate between 75-82% efficiency, consuming much less AC power.

I'm not trying to stop you from building your rig, I'm just curious how much power you'll really need.

[Hijacker]

Those are max numbers. Not average numbers.

The Phenom is rated as a 140W CPU, but it rarely pulls 140W.

AMD has on their site recommended PSU sizeQuote »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 CrossFireXâ„¢ technology in dual mode) [/quote]According to Tom's Hardware, the 4870 pulls quite a bit of power on load:

In fact, that number is over the max I was using from PC P&C. I'll recalculate that later...

Anyways, I've already settled on the 1350W Coolmax PSU, and I have my antec 550W I can split the load with. That's a combined 1900W of total power.

One thing to keep in mind is that even though a power supply is rated for a specific consumption rate, it will actually rarely use that much. Higher consumption rating doesn't always necessitate higher actual consumption. If I have a system that is drawing only 500W, it doesn't matter to me if the power supply is rated for 500W or 1000W. The system is only demanding 500W. In fact, the closer you bring a PSU to its ceiling, the worse off you are. By overworking the supply unit, you run into stability and longevity issues. Hence why I don't mind working with a 50% overhead ceiling.

Power usage is determined by voltage and current ratings. So long as those don't increase, power usage doesn't increase. That's why when CPUs and GPUs are idling, they pull less voltage to decrease power consumption.

You're mixing effeciency percentages with usage percentages. Effeciency is how much power is lost during the conversion from AC voltage to DC voltage. The PSU is a transformer that converts incoming AC voltage into multiple DC voltage and then regulates. There is an effeciency ratio involved in the process where the power that is lost during the conversion is bled off as excess heat. The higher the effeciency, the less heat. The less heat, the more fun time your PSU gets to have.

[Looneybomber]

The graph you've posted I've not seen before. I'm glad you linked to that card, because now I will read that review. I'm curious about each site's testing methodology. If the 4870 consumption averages 153w, but peaks (short term burst) at 283w, that's nearly a 100% increase. I'm curious as to how long it can maintain a 250w+ consumption. I'll have to look into it. I've thought about the possibility of adding a second 4870 later if the need be, but with a 625w PSU, at peak consumption, my PSU might not be up to the task.

As for the PSU usage and efficiency, I wasn't mixing them up. At very low usage, a PSU's efficiency is also low. Around 40-80% usage, they're typically the most efficient. Outside that range, their efficiency drops, though typically not too much from 70-100%. From 20% and below, some perform pretty poorly.

Here's the info on the PSU I bought...which I bought for it's quietness. It's the most silent actively cooled PSU tested by silentPCreview.com so far.

[Hijacker]

I see where you're getting at now. I was thinking of efficiency at a constant usage level.

Anyways, after consulting with some of the best rig builders I know, my calculations are correct. I overestimate with a 50% usage overhead, but the average overestimate is 30-50%. So long as you're in that range, you're good to go. And so long as you're utilizing the PSU at a 50% and over capacity (including idle times and whatnot), you won't have to worry about effeciency of conversion dropping to a critical level.

Let's take my rig setup for example. At peak, I expect it to draw about 1330W (I adjusted for the increased power of the 4870). My PSU should never have to draw more than that.

Using a 40% overhead (I'm looking at the midground because 50% was putting my adjusted numbers over the 2kW mark), I come out with needing 1,875W. The 1350 I want combined with my old 550 would make an easy 1,900W. I'm utilizing 70% of the PSUs' overall capacity. That's a nice meat of the range. I unfortunately don't have the actual numbers for either of my potential PSUs on range of efficiency. So let's say that the 1350 (which meets the 80% standard) is on an even 80% effeciency rating.

If I task the 1350 with powering my 3 vid cards, the HDDs, the DVD drive, and the case fans, I have a total load of 969W at peak (71% max capacity). With an 80% effeciency rating that makes it require 1,211W.

At lower consumption of idle speeds, I expect to see a guestimation of 529W. That's 40% of capacity give or take. I can't be accurate with that number as I don't know the idle consumption of the HDDs, the fans, or the optical drive. So again, I'm still above that horrible 20% capacity margin at idle. Now, let's say that at this range, I'm only at 70% efficiency (a made up number, but I can safely guesstimate it would be close to around that in my experience). The PSU only requires 661W for conversion. Not bad for all that jazz.

My 550 isn't as efficient as it's 3 years old and the requirements were much more lax when it was made. Personally, the best solution would be to try and find a newer PSU that meets the 80over standard and utilize it. But I would use the smaller of the two PSUs to run the mobo and proc. The mobo would draw its power, as would everything attached to it. CPU, RAM, PCI cards. I personally expect it to draw at peak 370W (67% max capacity). With headroom, I would need 518W. The 550 wins again!

I'd have to look specifically, but I'm pretty sure my PSU was made when 70% was the standard. So at peak, I would see probably 528W of incoming AC needed.

At peak, I would expect a total needed input of 1,739W AC once I split the load up between my two units. But a lot of my numbers are educated guesses. One thing I want to do is contact Coolmax about the 1350 and get variable load data if possible. I've seen variable load data on some of their lower end 80over units, and they perform pretty well. The Antec 550 I have is outdated, but it would get the job done in a pinch.

The biggest thing to make sure is that a rig of this size would need a very well made UPS.

Of course, if I was looking at building mid-range, this would all definitely be too much. I'm looking at maxing potential with the best of the best equipment I can buy.