Who is running Dual Power Supplies?

I just ordered a 6800 Vanilla AGP video card and I have been told that I should run dual PSUs to get the max out of it. I found a nice little article on how to do this. I have two power supples: a 400W and a 250W.

Anyone have any experiance with this? How much differance is this going to make?

I am planning on unlocking the four pipes, and overclocking the card by a modest amount.

You do not need two PSU's for any card unless you want one to do the cooling/lighting and the other one to control the motherboard and main components.

400+ Watts would be good, with an amp rating of 24A+ I would say. I have an Aspire 520W PSU with 34A @ 12V and it powers the following:

AMD 4000+
7800GT
1GB OCZ Premier Value
2x 74GB Raptors
4 Fans

So I don't quite think you need all of that.

Get just one good one as Techie suggests. I personally like the Enermax power supplies myself and would go with 400+ watt also.

Most modern power supplies will have a separate power dongle that's for the video card specifically now.

Agreed with the above. I tend to go with Antec, Enermax, Coolermaster, and other well known brands of PSU's. Definitely go 400+ if you're mounting any power-hungry graphics board or running SLI/Crossfire.

Yeah, and if you are confused what a power dongle is, as I was when I first started getting into computers, a power dongle is just a power cord that comes from your PSU. Normally they are 4-pin, and can also be referred to as "Molex Connectors" But, some video cards use little 3-pin connectors, not many, but some.

Hmm, well I am starting to rethink my plan. My main problem is that my current PSU does not have enough "dongles" for my new card. I think I can get a splitter, but is that recconmended?

Sorry about that Techie ... didn't mean too use pure tech terms.

When I got a new machine I spent the most money on the Motherboard, PowerSupply, and Ram. CPU and video is secondary for me.

You should buy one nice $80+ Power supply. I would avoid splitter if possible. Make sure it has some SATA (serial ata hard drive power connectors) and one or two more power connectors’ devoted to a video cards.

Reason why I focus on Mother Board, Power supply, and Memory over CPU / Video card.

If you change your mother board latter, you will most likely be changing other things, such as cpu, memory. So get the best mother board you can at the time of purchase.

Power supply - 2 reasons. One cheap power supply = lots of windows issue you will hard time trying to trouble shoot due to power dips that make everything else look like it's an issue. Get a top quality one and get and high watt one so it will last you 2 may be 3 upgrades.

Memory, if you get the fastest memory for your board, your not likely to upgrade latter unless your also doing a new mother board or need to expand the amount.

Now then CPU / Video card because there will be faster better stuff you can upgrade too even if you bought the system with top of the line at the time.

Point is make a good foundation first with Motherboard, Ram, and Power supply.

Also consider getting an UPS (uninterrupted power supply). You want the type that has the AC charging a battery, your PC is running of the battery.

When power goes out, you have 5-30 min of battery power to turn off your pc correctly and give you "pure" voltage going to your pc, no power spike or drops.

Splitters will work so long as 1) You have 400+ watt PSU 2) you DON'T connect both video card power inputs to a single power lead. This is a big no-no. Each video card power connector should have its own power lead coming from the PSU, with each outgoing split going to another hard drive, CD-ROM, etc.

GPU's are one of the most watt consuming parts of a computer. If anything, DO NOT have them share leads with another component. You can use splitters on things like HD's and what-not however.

Got it, got it, got it. In fact, I have had been dealing with a video card that is far below the quality of the rest of my system for some time now. I finally am getting up to the video card, since I have this thing about running everything at 1600x1200 and I am sick of running at low quality.

Lord_Shar, I think we might have our wires crossed somewhere. I am running a single Video card, so I think I only have one input. I get the thing about not splitting the lead to the card, but you lost me there.

I have been really impressed with this PSU so far, it replaced one that died after a month of operation, and has not hampered my use at all (as well as lowering my opertion temp by 10 degrees C at max use. I am fairly confident that the power output is strong enough, I just wish it had more leads.

I am starting to think that I should hook up both power supplies just because I have two available. Or just split the inputs to the CD-ROMs and hard drives so that I have enough leads to the video card.

Then use the weaker one for lighting/cooling. Use that one for your fans, and maybe to power your motherboard depending.

Use your stronger one for the GPU's/IDE's/etc.

And what PSU do you have exactly?

Err, well, the 250W is a Dell Stock unit. I knew that would not be enough long ago. The 400W, well I will have to look at the name on it, I will check that out when I get home. I credit the differance in temps to the low quality of my last one, and the 120mm fan on it.

Some video cards, like my 6800Ultra, have two power inputs. If you only have a single video card power input, then sharing a power lead between it and a semi-active device like a CD-ROM should pose no problems.

OK, so it is an SP P4 400W power supply, with 120mm fan.

So, stronger one for the GPU and IDEs, should I run my mobo on that one too? If you think so, then there is virtually nothing to run with my smaller PSU, since most of my fans run of the mobo and my lights are only LEDs in the fans.

I think I catch your drift lord_shar. I also think the Vanilla version only has one power input, but I could be wrong, since it only shipped today.

Thanks for all the help so far by the way. I love bouncing ideas like this off of people.

Vanilla only has 1 power input, a 4 pin molex connector.

And the Dell PSU's are very reliable, but not a very high amp rating. If you notice on the tag on your 400W PSU you will see a column with "12V" under it should be "#A" Where "#" is an integer. Could you possibly tell me what that would be?

You know when you shutdown to do a little exploratory surgery and forget exactly what you were looking for? That is me right now. I have every number written down from my power supply in front of me.

Well, at 12V it is 14 Amps. For comparison the 3.3 and 5V are 30 and 40A respectively.

The Dell 250W has 16A at 12V..... much less at the other voltages. Comparing mine with the numbers from your earlier posts, I suddenly wonder if that 400W tag is for looks only...........

Well a friend of mine, PieXags PM'ed me asking for video card advice. He said he wanted to get an x850XT PE, but he has a Dell Dimension 8300. He searched around on Google, and oddly enough, he found posts of users having x850XT PE's and 6800GT's in their system.

So I guess I am wrong, you could probably use the Dell one.

Maybe I should run dual power supplies, since my 12V amperage is so low.

I am thinking the Dell with it's 16A on the Video card, and the 400W with it's 14A on the Mobo and IDEs......... at least till I get sick of having 2 power supplies and get one with about the same amperage as the two combined.



Edit: Does the Video Card run on the 12V then?

Almost every component runs on the 12V rail. And I am telling you from my own advice not to take a risk and try to run it under the recommended wattage and amp rating.

Hmm, well the manufacturer does not provide any real data on the input side of the card. It says a 400W power supply is required.

/gee thanks for all the help, NOT

Maybe they choose to believe that gamers don't understand difficult numbers like dq/dt.

/end rant

Anyway, I sent a support request and hopefully they can tell me how many amps the 12V side needs to produce.

I suspect that since my 250W supply has a higher amperage rating (@12V), the video card would be happier with it, but I am still speculating. I need the numbers.

Thanks again for all the help. I think my knowledge of Power Supplies has doubled in the last 24 hours

Just for kicks I started looking...... I am almost completely convinced that the chart is completely full of made up numbers.

Check out this PSU

http://www.tigerdirect.com/applicati...174&CatId=1078


Sorry, but I seriously doubt that 120 amps are available from any power supply.

In fact here is the proof. I am doing the equations right here.

P=iV
p=120A 12V
1440W from a 400 watt power supply?

Wow, now lets add up the other numbers.

P=3.3V x 20A + 5V x 38A + 120A x 12V
P= 1696 Watts.

Wow, a new reccord!!! all from a $21.99 400W power supply. Talk about value!!!!

I think I may just plug it into my 400W power supply and see if I get that message that says the card has been de-tuned for the lack of power it has available.

When it comes to PSU's, you get what you pay for. A good 400+ W PSU should be in the $40-50 range. My 520W Aspire ATX PSU has 34A @ 12V and costed me $60.

Btw, Newegg is a lot better than Tiger Direct.

www.newegg.com

Ahh Tiger Direct is better from a shipping/recieving standpoint. 2 working days to get my 6800 to me. I am running the 400W power supply, however I will soon be running benchmarks with a second power supply dedicated to the video card. If that inproves the performance at all I will take new action. I did get all of those pipes unlocked and the shader.

Wow, I love this card!!!!!!

I went from 249 on 3D Mark 2005 (with my 5200) to 2469 with the new card, then I got to 2745 by unlocking the pipes and shader. I know there is more available, but I want to ensure that my driver is the best for my card and I have enough power before I really try and push it.

Even the most equipped gaming PC you'll ever see would be less than 300W constant. In fact most SLI systems are around 200W. A non-SLI rig sits usually at 150-170W or so running 3dmark, unless it's a recent P4 system (they suck a lot more power).

Very few people (read: SLI people) need more than a 400W PS. These power supplies actually supply only around 290W or so constant at max, with a peak power rating of 400W (what you see on the box). The efficiency of the more expensive supplies (Antec, Enermax, PC Power Cooling, etc) is a lot better because of quality construction, and having a good bit of headroom with a 400W supply will improve efficiency as well. The power supply needs to run cool and be loaded with good heatsinks or its efficiency will plummet, along with its longetivity and stability. Enermax is probably best, second to the noisy, expensive, but very high quality PC Power & Cooling supplies.

I find the whole power supply obsession fascinating. The marketing for "high-end" supplies is quite entertaining btw.

DO NOT buy a power supply that costs <$50 or so or you are just asking for trouble because it will be cheaply made. It will be less efficient for certain (and probably have other issues) and thus you will pay more for its wasted electricity (not trivial with today's PCs). You can go to Newegg and buy a 500W for $25 if you want, but I guarantee it will never push near 500W.