The truth about 12V amperage

[Angerisagift]

I'm rebuilding my P4 system with parts that I'm getting for Xmas, and am pretty sure the person who's supposed to get the power supply is going to flake, so I'm leaning towards getting myself a Corsair VX450W once my wallet recovers from the holidays.

my question is, how much amperage is enough, and what happens if I run under amperage.

the system I'm planning

Q6600 2.4ghz
ECS 671-T motherboard (part of CPU PROC combo)
2GB OCZ DDR2 Dual Channel Kit
xfx 8800GT 512MB

existing components to be used

1x 80GB SATA HDD
1x 80GB IDE HDD

Raidmax 420W 12V 13.0A PSU

Raidmax Scorpio ATX case with 6 80mm fans.

my question is, would a system like this even run at this amperage even if just for a few weeks until I can get a better PSU

they typically recommend a PSU with 22-26a on the A12V rail for the 8800GT, but I know it doesn't use anywhere near that much alone.

I wish I could buy all the components at once but just haven't had a lot of spare money the last few years, and I finally got to the point I decided
"I want my upgrade damnit" and currently this is the only way it's going to happen.

anyways what are your thoughts.

 

[mpilchfamily]

If you go with that Raidmax PSU you will run into trouble. If you are able to get the system up and running it won't stay that way for long. Chances are the PSU will pop and let the magic blue smoke out. When that happens other system components tend to die as well. So if you value your new components then wait for the better PSU. As you mention you will want a PSU that offers about 26A or better on the combined +12v Rails. Yes on average the system will pull about 18A to 20A and then load up to 26A or better. Keep in mind the 26A is total system. So just wait and get that VX450.

 

[Yellowbeard]

Originally posted by: Angerisagift

Q6600 2.4ghz

xfx 8800GT 512MB



Raidmax 420W 12V 13.0A PSU

IIRC, the TDP for a Q6600 is 105w aka 105w/12v = 8.75a. The video card will probably max out at 170w or so, 170w/12v = 14.16a. Based solely on the CPU+GPU at approximately a 43% load, your power supply would be asked to provide 100+ load on the 12v rail which is a BAD idea. See the gruesome description above by Mpilchfamily.

 

[imported_Scoop]

You could read the shuttle article on the Anandtech front page. Running an OC'd Q6600 with an 8800GT is no problem for a 250W PSU with a single 16A 12V rail

 

[BladeVenom]

Originally posted by: Scoop
You could read the shuttle article on the Anandtech front page. Running an OC'd Q6600 with an 8800GT is no problem for a 250W PSU with a single 16A 12V rail

Shuttle also probably uses a better power supply than Raidmax. Those cheap power supplies usually can't reach anywhere near what they say they can.

Would you vouch for the quality of a Raidmax power supply?

 

[SerpentRoyal]

Overclocked Q6600 @ 3.7GHz...200 watts
8800 GT...110 watts
HDD x 2...30 watts

A quality Earthwatts 380 ($20 AR) should do the job if you're tight with cash flow. Better option is to watch HOT DEALS forum for $30 AR Earthwatts 500.

 

[imported_Scoop]

Originally posted by: BladeVenom

Originally posted by: Scoop
You could read the shuttle article on the Anandtech front page. Running an OC'd Q6600 with an 8800GT is no problem for a 250W PSU with a single 16A 12V rail

Shuttle also probably uses a better power supply than Raidmax. Those cheap power supplies usually can't reach anywhere near what they say they can.

Would you vouch for the quality of a Raidmax power supply?

I didn't actually read the whole post, just threw that in for these ridiculous claims of wattage/amperage needs.

The thread starter says the raidmax has a 13A 12V rail so no I wouldn't recommend it. I would go for a Seasonic S12II-330 just for that system. If you're thinking of keeping the PSU for a longer time and maybe sometime down the road using a GPU that uses two pcie cords, then something more powerful.

 

[Leros]

Listen to these guys. Don't cheap out on the PSU. I bought a medium quality $40 PSU for a computer I built a few years ago. I was having some rebooting problems. Then one day. *Poof* CPU dead, RAM dead, mobo dead, graphics card dead. $800 later I had a much downgraded computer.

 

[The-Noid]

Originally posted by: SerpentRoyal
Overclocked Q6600 @ 3.7GHz...200 watts
8800 GT...110 watts
HDD x 2...30 watts

A quality Earthwatts 380 ($20 AR) should do the job if you're tight with cash flow. Better option is to watch HOT DEALS forum for $30 AR Earthwatts 500.

Recommending an Earthwatts 380 is almost criminal in this situation.

Not only does it not have near enough on the 12v. The motherboard, fan, cd-rom, sound card, and numerous usb devices will overload his psu.

Also the fact that psu's degrade over time (you make this point in * threads).

 

[Angerisagift]

As much as it pains me to wait, and I've been waiting a damn long time to do this upgrade, I'd rather wait an extra week or two, and pick up a decent PSU

currently I'm leaning in these directions

http://search.dell.com/results...&k=corsair+450&cat=all

http://accessories.us.dell.com...=en&cs=19&sku=A1311687

http://accessories.us.dell.com...=en&cs=19&sku=A1312491

will probably go the corsair route, have heard a lot of good things about this PSU

I'm married so SLI is not an option unless all of the sudden PC gaming catches on in a big way and hardware prices plummet to increase the install base. So as far as I know I"ll be running a single GPU unit for a long time.

My birthday is a month after Xmas, so anything I don't get for Xmas, I'll definitely be able to get by then, thinking about getting an Antec 900 for a new case, and might add a Tuniq tower to the CPU because from what I hear it's cake to get those Q6600's up to 3.2Ghz

I know I had my P4 2.6Ghz up to 3.0 on stock cooler, but I'd rather not be taking any chances with a quad and want to get something aftermarket for it.

 

[Yellowbeard]

Originally posted by: Leros
Listen to these guys. Don't cheap out on the PSU. I bought a medium quality $40 PSU for a computer I built a few years ago. I was having some rebooting problems. Then one day. *Poof* CPU dead, RAM dead, mobo dead, graphics card dead. $800 later I had a much downgraded computer.

VERY VERY TRUE! Sad, but true. Cheap caps are killers.

Also, an astute collegue pointed out that I had made an error in my GPU numbers. TDP on the 8800GT is either 105w or 110w depending on who you ask and not 170w. I'm admittedly very green on GPUs so excuse my mistake. I try to be accurate but, took something out of context from another discusssion.

Regardless, 13a on the 12v rail is a bad idea with this combo. 105w/12v = 8.75a for both the GPU and CPU at stock. That's 17.5a under heavy load there nevermind the HDs, MOBO, etc. So, CPU and GPU alone are still far in excess of what this PSU is rated for. As noted above, that type of overload can lead to a catastrophic failure.

Also, if you read around, some posters have accused Nvidia and ATI of grossly underestimating power draw on their GPUs. So, we don't really know how sound that 105w - 110w TDP is on the 8800GT if you believe the conspiracy theorists.

 

[Angerisagift]

Do you think 13a would be enough If I built the system without the GPU, the Mobo has integrated Mirage 3 graphics it would be nice to do most of the build initially and install the OS, then add the GPU once I've got the new PSU.

 

[Yellowbeard]

In all honesty, the PSU you have is not known for putting out quality power. I would not mix it in with newer parts if it were my system. I certainly understand budget constraints but, in reality the PSU is the backbone of a modern system in more than 1 way. It's like the foundation of a house really.

It is not nearly as glamorous but, you may want to buy your new choice of PSU first. Then, you can build up around that without fear of plethora of potential problems associated with using an older underpowered PSU.

 

[maluckey]

Everyone,

I can tell you first-hand about marginal PSU's. I followed the "popular" reccomendations and they failed....expensively. Sure, they were stressed heavily with OCing, but supposedly they could handle the workload. Don't skimp. Something that works fine for a day, may not last under extended conditions. I'm not even talking about derating curves, One brand (three separate PSU's in a row died), was rated in excess of my needs, but was filled with crap caps and poor heat resistance. The manufacturer offered an upgrade for cost of the difference in price after the third PSU. I turned them down for a refund.

I later went for the most stable PSU in my price/performance range, that had at least 20 percent unused overhead reserve. Never had an issue since.

Moral of the story? It's that you sometimes pay more for a cheap PSU when you add in the cost of the destruction it leaves when it fails.

 

[Angerisagift]

Now I have to wait so don't worry about me doing anything foolish,

My wife ordered a XFX 8800GT 512MB from Dell for me on the 4th, it was supposed to ship yesterday, and Dell delayed my ship date to the 28th, so no Merry Christmas to me,

I'm either going to buy the Corsair 450VX through Dell

or If I get a gift certificate to Frys, I'll go to the actual store and look for an earthwatts 430 or Thermaltake purepower 500W, they carry some silverstone PSU's too but only at 400W possibly the earthwatts 500 if the price is right.

http://shop3.outpost.com/searc...=-51720&pType=pDisplay

I've been paying attention to the forums

so I know what to look for

80% and up efficiency

which one weighs more (not always a metric, but a useful way to dismiss an unknown brand)



good amperage on the 12V rail, single rails with high amperage is better than multiple rail with higher combined amperage.

look for reputable brands that have been reviewed.

Seasonic
Corsair
Silverstone
Enermax
Antec

I think I got this in the bag

 

[Yellowbeard]

Sorry to hear about the delayed shipping. Good luck with the rest and have fun with the build.

 

[SerpentRoyal]

Originally posted by: Angerisagift
Now I have to wait so don't worry about me doing anything foolish,

My wife ordered a XFX 8800GT 512MB from Dell for me on the 4th, it was supposed to ship yesterday, and Dell delayed my ship date to the 28th, so no Merry Christmas to me,

I'm either going to buy the Corsair 450VX through Dell

or If I get a gift certificate to Frys, I'll go to the actual store and look for an earthwatts 430 or Thermaltake purepower 500W, they carry some silverstone PSU's too but only at 400W possibly the earthwatts 500 if the price is right.

http://shop3.outpost.com/searc...=-51720&pType=pDisplay

I've been paying attention to the forums

so I know what to look for

80% and up efficiency

which one weighs more (not always a metric, but a useful way to dismiss an unknown brand)



good amperage on the 12V rail, single rails with high amperage is better than multiple rail with higher combined amperage.

look for reputable brands that have been reviewed.

Seasonic
Corsair
Silverstone
Enermax
Antec

I think I got this in the bag

Have patience, Grasshopper. Watch the Hot Deals forum. You're see Antec Earthwatts 380/430/500 on sale starting at $10 up to $30 AR. These are built by Seasonic and are known to be compatible with many boards. The best value in PSU.