Corsair VX 450W or 550W

[marcplante]

I'm upgrading to an 8800Gt card and the EVGA specs ask for more amps than my current Coolermaster PSU offers (asking for 26A, I only have 22A), so I'm going to upgrade. looking at the corsairs at Buy.com and wondering if I should buy the 550W @ $67 vs the 450 @ $59.

Waondering if the headroom of the 550 is a good thing.

System:

MSI K8N Neo4 Mobo
Athlon 3800 X2 Proc
2 G of Kensington RAM (possible upgrade to 4 later)
8800 GT GPU (EVGA) (24" samsung monitor)
160 G Seagate PATA drive (could see adding a 320G SATA in the next 6 mos)
DVD-RW drive

The 450 seems to have some pretty hefty power on the 12V rail.

Would the 550 run moer efficiently? Seems like the 550W space is for a Quad core Proc? Doesn't seem enough power for SLI, so is the 550W PSU:

a) solid, conservative power for a system like mine? [not clear if Corsair is citing continuous or peak power]
b) Meant for more components than I have (How many more?)
c) a platinum coated solution for a PC like mine?

Thanks,

ps, yeah, i realize I'm between big deals on PSUs, though the pricing on the corsairs is good enough for me. I'm in the mood for a little retail therapy. It feels better if I spend a little more 8^D

 

[Doclife]

The VX 450W would be more efficient than the 550W in your system. Corsair PSU efficiency curve typically peak at around 50% load and rolling off (less efficient) on either side of the peak. Thus, if your system draw say 200W then 50% load on the VX 450W would be 225W, which is very close to the peak efficiency. On the other hand, 50% load on the 550W is 275W, and 200W load is a bit further from the peak efficiency.

Link to the efficiency curve of the VX 450W

http://www.silentpcreview.com/article751-page1.html

 

[andlcs]

Corsair is citing continuous power at 50oC. Both are high quality PSU based on Seasonic (VX450) or CWT (VX550) models.

Here's Jonnyguru's SLI Power Consumption Results:
http://www.jonnyguru.com//forums/showthread.php?t=3137

I think the VX550 can power the 8800GTSx2 + Quad-Core CPU system.

 

[DSF]

Originally posted by: Doclife
Link to the efficiency curve of the VX 450W

http://www.silentpcreview.com/article751-page1.html

I understand your point, but the graph exaggerates things a little bit. It looks like a huge dropoff on either side of 50% load, but in reality it's going from 84% efficient to 81% efficient.

 

[Doclife]

Originally posted by: DSF

Originally posted by: Doclife
Link to the efficiency curve of the VX 450W

http://www.silentpcreview.com/article751-page1.html

I understand your point, but the graph exaggerates things a little bit. It looks like a huge dropoff on either side of 50% load, but in reality it's going from 84% efficient to 81% efficient.

Yeah, I know. It is more of an academic exercise than anything else. The principle is that right sizing the PSU with the system load will not only achieve better efficiency but also save you money because you don't have to spend more money on big PSU that you don't really need.

 

[Yellowbeard]

For $8 more I'd get the VX-550 if I was buying gear and building a system.

 

[frankie38]

I decided on the 450 vs 550.

1) Save $.
2) Seasonic vs CWT.
3) 450 provides more than enough power on the 12v rail to power the 8800gt.

Have you considered that the 3800x2 might not be enough cpu for the 8800gt?

 

[jonnyGURU]

Originally posted by: Doclife

Originally posted by: DSF

Originally posted by: Doclife
Link to the efficiency curve of the VX 450W

http://www.silentpcreview.com/article751-page1.html

I understand your point, but the graph exaggerates things a little bit. It looks like a huge dropoff on either side of 50% load, but in reality it's going from 84% efficient to 81% efficient.

Yeah, I know. It is more of an academic exercise than anything else. The principle is that right sizing the PSU with the system load will not only achieve better efficiency but also save you money because you don't have to spend more money on big PSU that you don't really need.

Right.... but in the case of the VX450 vs. VX550W, they are both the same efficiency (about 83%) at 20%+ load. And I have found that the VX550W is actually MORE EFFICIENT at lower loads than the 450W.

Note:

VX450W: http://www.jonnyguru.com//modu...iews&op=Story2&reid=64

VX550W: http://www.jonnyguru.com//modu...iews&op=Story2&reid=62

Ignore test 1 on the 450W since that is a crossload. Go to test two. 95.7W is 79% efficient. The 550W was 80% with a 87.2W load.

Now move to test three on the 450W and test two on the 550W. At 195.2W the 450W is 83%. At 166.4W the 550W is also 83% efficient.

Fact is, the difference in efficiency between two different efficient unit is negligible, typically only one or two percent, unless you're talking about a 450W vs. a 1000W and your load is only about 150W. I, for one, would rather have a slightly larger PSU that is running cooler, has the fan running slower, that is bound to last longer and offer more overhead if I decide to upgrade something in the future.

 

[Yellowbeard]

Originally posted by: frankie38
I decided on the 450 vs 550.

1) Save $.
2) Seasonic vs CWT.
3) 450 provides more than enough power on the 12v rail to power the 8800gt.

Have you considered that the 3800x2 might not be enough cpu for the 8800gt?

I'm not discounting your personal preference but, the CWT is equally as good as the Seasonic models. We made sure of that before we selected them to build our PSUs.

 

[marcplante]

I'm slipping down the spiral of retail therapy. After a couple quick PMs with Johnny Guru, I decided that:

a) I wanted a little more headroom, so no 450
b) modularity is a good thing (no particular reason since my box isn't THAT crowded, but still a good thing), so I'm going to buy the 520.

Now I'm bottom feeding to update the x2 3800 Processor so I'm not CPU bound.

Looks like this is my new habit since I can't get my car to the track anymore. The driving sims will look good on the new monitor we got for my wife's "home office" (not tax write off, mind you. That's fraud...just emotional justification).

Thanks for all your input. This site ROCKS!!!

Marc