What voltage PSU do I need for this workstation configuration?

[classic35mm]

EDIT
Sorry. I should have said what wattage (not voltage) PSU do I need. I'm not sure how to change the thread title.

I'm not an IT person or computer expert. I am considering a Lenovo ThinkStation P300 Tower with the following configuration (Windows 7):

Xeon E3-1241 v3 (8MB Cache, 3.50GHz)
8GB PC3 1600MHz uDIMM
NVIDIA Quadro K420 1GB (DVI+DP)
16x DVD +/- RW DL Win 7 only
2.5" 256GB SATA SolidState Drive
3.5" 2TB SATA HDD 7200 rpm

The P300 is available with these two different power supplies (under the "Form Factor" section on the configuration page):

Tower with Intel C226, 280W 85% [included in price]
Tower with Intel C226, 450W 92% [add $50 US]

Should I get the 280 W or the 450 W power supply?

I asked that question to two Lenovo reps, separately, and I got these answers.

You will want the 450W power supply if you ever plan to make any upgrades such as a higher end graphics card. The 280W is pretty small and cannot handle upgrades much past the base specs. If your configuration on lenovo.com requires more power, it will default to the 450W.

The short answer is that the configurator (online) shouldn't allow you to configure the system with a PSU that is not sufficient to support the configuration. Generally, the 280W is sufficient for most configs. The 450W comes with a 6 pin aux graphics power cable that is capable of supporting up to a K4200 card in the tower. The K4200 card is rated at 108W, so it requires additional 12V power beyond what the PCIe slot provides in order to function.

I'm not sure if those two answers are completely in agreement or not. On the one hand, I would like the option to upgrade down the road (e.g., additional memory, additional hard drives, perhaps an additional optical drive). On the other hand, I do not expect to upgrade the graphics card, at least not to something as expensive as the Quadro K4200.

When I use Lenovo's online configurator and load up a P300 with some top specs (Xeon E3-1281 v3, four 8 GB sticks of ECC RAM, two 4 TB HDDs, two Bluray drives, and even the Quadro K2200), the 280 W PSU is still an option. It's only when I select the Quadro K4200 that the configurator forces me to choose the 450 W. So I'm not entirely confident.

So I decided to try Cooler Master's wattage calculator for the system I mentioned at the top of this post (Xeon E3-1241 v3, 8 GB non-ECC RAM, Quadro K420, DVD RW drive, 256 GB SSD, 2 TB HDD). I think that the Xeon E3-1241 v3 is FCLGA1150, so I selected "LGA1150". Cooler Master doesn't have the Quadro K420 (45 W max) listed as an option, so I chose a card from their list with a similar wattage (Quadro K600: 41 W max). And, "the Oscar goes to ..."

... Cooler Master tells me that I will need a minimum PSU of 272 W. I realize there may be some "fudge factor" included in the calculation, but still, that's awfully close to 280 W, it seems. Another thing is that my existing computer, a desktop from 2007 by another manufacturer, has a 375 W PSU. I don't want to "downgrade," if that's the right word.

So, what are my options? Do you have any advice?

• I guess one option is to just go with the 280 W, but wouldn't I be risking unexpected shutdowns and general wear and tear?
  
• Another option is to go with the 450 W, which is probably a lot more than I need. Since it is oversized for my purpose, it might run inefficiently and cost more power from the wall. Are there other risks associated with a too big PSU?

One other question I have is, which option would lead to a hotter (or at least noisier, due to fans running more) machine: a too small PSU or a too big PSU? I'd like to keep the temperature and noise down in the room as much as possible.

Thanks so much for your time and patience.

 

[mikeymikec]

I'd go for the 450W. As I understand it, PSUs become less efficient over time (ie. at one time PSU X could supply 300W, a few years down the line it can only do say 280W or less), so I'd go for a bit of overkill with the aim of having a PSU that lasts no matter what.

 

[classic35mm]

Thanks, mikeymikec. Besides price, are there any potential disadvantages with going for the 450 W over the 280 W?

 

[mikeymikec]

Assuming that they're both the same brand and series, and there aren't any peculiarities to one model or another, there's no disadvantage of going with the higher wattage model.

 

[ignatzatsonic]

For the 50 dollar differential, I'd be sorely tempted to get the 280 watt PSU, then immediately replace it with a separately purchased 400 to 500 watt PSU of my own choosing---using the $50 I saved.

Might add another $20 or $25 into the pot.

Put the 280 watt model in the closet for emergency use only.

You'd at least know you had a quality PSU rather than whatever Lenovo is offering this week.

 

[mikeymikec]

For the 50 dollar differential, I'd be sorely tempted to get the 280 watt PSU, then immediately replace it with a separately purchased 400 to 500 watt PSU of my own choosing---using the $50 I saved.

Might add another $20 or $25 into the pot.

Put the 280 watt model in the closet for emergency use only.

You'd at least know you had a quality PSU rather than whatever Lenovo is offering this week.

Not a bad idea, but warranty-wise things might get interesting if the OP ever needs to get it repaired under warranty.

 

[SERPENTINE]

A 500W MODULAR HYBRID PSU would work well. Just make sure you don't get a PSU with too high of a wattage because it can actually degrade performance. Anyhow, make sure you get a great known brand like Corsair because cheap PSUs are known to start fires and become faulty after minor use. Check for 80 PLUS, Bronze, Silver or Gold . :biggrin:

 

[classic35mm]

Thanks so much for your time. When you say "it can actually degrade performance," do you mean performance of the system as a whole (processor speed, processor flops, read time of the hard drive, etc)? Or do you mean the efficiency of the PSU drawing power from the wall (lower performance = more system heat and higher electricity bills)?

 

[SERPENTINE]

Thanks so much for your time. When you say "it can actually degrade performance," do you mean performance of the system as a whole (processor speed, processor flops, read time of the hard drive, etc)? Or do you mean the efficiency of the PSU drawing power from the wall (lower performance = more system heat and higher electricity bills)?

No it won't degrade your PC's performance, but it'll hurt your wallet in terms of power efficiency.

There are a couple factors.

• One, the load you'd place on the PSU. Click here to determine how much wattage your PC uses.
• Two, the efficiency of the PSU (80+, Bronze, Silver, Gold and Platinum). For a great video explaining 80+ PSUs click here! Here is a link to a website that displays all efficient (80 plus and higher) brands that you can easily find on Amazon or Newegg. :biggrin:

Power Supply Efficiency: Definition
Very simply put, power supply efficiency is the output power divided by the input power:

Read the rest at the power-supply-designer website! There are a few more factors to account for, so make sure you read that article.

I suggest getting a PSU that is slightly higher than recommended just in case if you ever wanted to upgrade your GPU or something like that. Make sure that you get a Hybrid-Modular PSU or a full blown Modular PSU because some connectors will be needed for newer GPUs like 6+2 pin and 6 pin PCI express cables which usually come with the PSU itself. Another benefit to a modular/hybrid PSU is the amount of space you'll save in your case.

If you have any more questions, please reply

 

[cruzinforit]

It's pretty simple. If you plan on adding a graphics card later, get the higher wattage power supply. If you don't, save your money and get the 280W. Power supplies don't really get less efficient over time, or lose ability to supply power. What typically happens, is capacitors go bad, which results in high ripple current, or unstable voltages which can cause system instability, in which case you'll want to replace the PSU anyway.

A 280W PSU will be fine if you don't ever plan on adding a graphics card to it. Most computers sold over the years come with 250-300W power supplies.