Necessary Wattage

[Unknown Person]

I've already selected all of the base components of my build, and have been planning to use the Corsair TX650, which seems to be a very good power supply at a good price. However, I'm wondering if that wattage is necessary? Here is the part rundown:

Intel Core 2 Quad Q9550 (waiting for the Aug 10th price drop)
ASUS P45 P5Q Pro Motherboard
ATI Radeon HD 4870
ATI Radeon HD 3650 (running 3 monitors + HDTV with these 2 GPUs)
4x 2GB DDR2-800 OCZ Reaper HPC
2x Western Digital Caviar SE16 640 GB
2x Samsung DVD Drives
Blu-Ray Reader/Writer (in the future probably)
Antec P182

I know that the 650 Watts would be more than enough, but I want to consider getting a modular PSU. The HX620 would be nice, but is around $50 more than the 650W. The HX520 is at the perfect price, but I'm not sure if this build could work with that wattage. I am fairly sure that I'm not going to be doing any upgrades on this computer for the lifespan of the computer (if it is anything like my current one, around 3 years), so needing extra watts is not necessary. Is the extra $50 worth modular cables? Should I get the HX520, or stay with the TX650?

 

[HOOfan 1]

HX520 should work fine.

If you are really concerned thoughhow about this

 

[Unknown Person]

I'm not really that concerned, I just want to buy the most conventional PSU that has enough wattage for my parts. I don't want to buy any more than I have to, since it's unlikely I'll add or change any parts to this build. If the HX520 will be able to handle it without any problems, then I'm up for it. Any other people have any experiences with this power supply?

 

[beray]

You should get something more than the 520HX, it can only do 80W max for 3.3V, you configuration is already at ~80W max demand for 3.3V.

 

[HOOfan 1]

Originally posted by: Unknown Person
I'm not really that concerned, I just want to buy the most conventional PSU that has enough wattage for my parts. I don't want to buy any more than I have to, since it's unlikely I'll add or change any parts to this build. If the HX520 will be able to handle it without any problems, then I'm up for it. Any other people have any experiences with this power supply?

a little overhead is never a bad thing. If you can afford it I would go a little higher, but really even if you were running both of those videocards at load at the same time then I think HX520 should easily handle the system.

But since the 3650 and 4870 are not able to crossfire, you really won't be having both cards at full load at the same time.

 

[Yellowbeard]

Due to your overall 12v load, I'd suggest the HX-620 or the TX-650. You can decide if budget or modular goodness wins out.

 

[Unknown Person]

Hm, so I used the power supply calculator (at http://web.aanet.com.au/SnooP/psucalc.php), and since it didn't support multiple GPUs of different models, I selected 4870's in CrossFire just to test, and got a 518W and 36.6A reccomendation for a "decent" brand. I don't know if this is accurate, but what exactly makes this system require 650W? I'm just curious, because I'm already stretching my budget, and I'd really like to get one of those modular Corsair PSUs if possible.

On the other hand, I'm totally not afraid of over-estimating the wattage, but wouldn't a higher watt PSU use more power than a lower watt PSU even if the components don't use that much (which would effectively make the higher watt PSU less efficient)? I'm a bit concerned of power consumption because I tend to keep my computers on 24/7.

 

[Yellowbeard]

24/7 usage is not a big issue with our PSUs as they are all 80%+ efficient. Try plugging your system requirements into our PSU Finder: http://www.corsairmemory.com/psufinder/default.aspx

 

[Yellowbeard]

Originally posted by: Unknown Person but wouldn't a higher watt PSU use more power than a lower watt PSU even if the components don't use that much ?

ANd, no this is not the case. The component power draw will be the same regardless of the PSU. If the components draw 400w under load, then they will pull the same amount of power from a 500w PSU as they would a 1000w PSU. Efficiency will play into it here of course but, you are talking about pennies per month difference.

 

[Unknown Person]

Originally posted by: Yellowbeard
The component power draw will be the same regardless of the PSU. If the components draw 400w under load, then they will pull the same amount of power from a 500w PSU as they would a 1000w PSU. Efficiency will play into it here of course but, you are talking about pennies per month difference.

Hm, that's nice to know. I used the Corsair PSU Finder, but it would only allow me to select one video card, or two of the same model, which isn't, in my case accurate since I'm running a 4870 and a 3650. Using the PSU Finder with just a 4870 (plus 2 harddrives and the Core 2 Quad), it recommends even the VX450. I don't know how much power the 3650 consumes, but I'm assuming it isn't a lot because it doesn't need to take extra power from the GPU with any PCI-E power connectors.

Simply put, I'm a bit confused of how much power I need, since some people are saying yes, and some are saying no, and I'm not sure if these PSU calculators are accurate. If the 520w is too little, then I'll go with the 650w, since the 620w is out of my price range. I'd like modular cables if at a reasonable price and not sacrificing performance, reliability, or quietness.

 

[Yellowbeard]

I realize now that I misread your post earlier. I thought you were asking about 2 x 4870s. An HX-520, VX-550, or TX-650 will all easily power this system. About 8 days ago, I ran 2 x 4870s in Crossfire with no issues using the HX-620. So, the 520 will easily run your rig if you want modular. The others are great choices also if you don't want modular.

 

[Unknown Person]

Ah yes, this sounds about right. Thanks for all of the help! I'm happy that I can go with modular and not stretch the budget.

 

[Yellowbeard]

Cool, sorry for goofing it up the first time. I read over your post too quickly.