Seasonic vs OCZ for 8800

[skyguy]

Am planning on doing a build for a friend.....list isn't finalized, but assume:

-6600 OC'd to 3.2 ghz +/-
-3 hard drives
-some LED fans, air cooling
-Either 8800 GTS or GTX in SLI (undetermined at this point)

Trying to decide whether he's going with the GTS or GTX, so my question is two-fold:

1) Will a Seasonic Energy+ 650w be enough for 8800GTS in SLI?
2) Will an OCZ GameXstream 700w be enough for 8800GTX in SLI?

If "no" to either 1 or 2, what would be the recommendation for an adequate PSU instead for that option?

Much thanks.

 

[jaguarskx]

Since I am an owner of a Seasonic 12 500, I highly recommend the Seasonic over the OCZ PSU. I researched PSUs for 3 months before I finally decided on the Seasonic last year.

Here is my estimate of the maximum load on the the 12v rails using the following hypethetical system:

E6600 @3.2GHz..............................................73w CPU power consumption
2 8800GTX in SLI mode.................................292w GPU power consumption
3 500GB Hard Drives.....................................66w
2 DVD Drives................................................32w
3 120mm LED Fans........................................21w

Total Estimated Power on 12v rails................484w
Total Estimated Amps on 12v rails.................40.3a

All other components draws power from the 3.3v/5v rails.

Based on the CPU power consumption graph I estimate about 7w of power for every 300MHz above X6800 stock speed.

I highly, highly doubt in a dual GPU system both video cards will be stressed to the max. But that's just speculation on my part since no review site has measured GPU power consumption in a dual GPU system.

Note: Although the Seasonic's Energy+ 650w PSU label states it has 4 12v rails, it actually only has 2 12v rails providing the 52 amps.

 

[skyguy]

Wow Jag, thanks for the info there, I appreciate your time and calculations!

I am well aware of Seasonic's excellent reputation (and checked Johnny Guru's reviews too) and would love to use one. While the OCZ is no slouch, I think the build quality, performance, and lack of noise of the Seasonic is the clear winner. However, I wanted to make sure that the Energy+ 650w would provide enough juice.

I was a primarily concerned that 650w wouldn't be enough, given that some people are using 750w or more for 8800 SLI systems...... :!: :?: I just want to make sure there's enough if he decides to go liquid cooling or add more stuff......which was why I considered the OCZ @ 700w. I know it can't compete with Seasonic for build quality, but that extra capacity at a very attractive cost got me wondering...........


One question about the 12v rails though: you stated that it actually has only 2 rails (not 4), providing 52A total. Does this pose a problem, or does it not really matter?

 

[jaguarskx]

Some people are dropping in 750W+ PSU into their 8800GTX SLI systems because they simply over estimate the amount of power a PC uses. For example, someone recently recommended a 500w PSU for an overclocked E6400 and a 7900GT. I pointed out that even a good Enermax 300w PSU have more than enough amps to power such a system with 2 HDDs & 2 DVD drives.

Having 2 instead of 4 12v rails is no problem. In fact, I believe it was JohnnyGuru who revealed this mislabeling in one of their recent Seasonic PSU review. I forgot the exact reason, but I think it was something like while the newer PSUs can support up to 4 12v rails, only 2 12v rails are currently provided.

 

[skyguy]

Cool, thanks for the info. I may re-read Johnny's Guru's reviews and check his forums for any further info on that.

Much appreciated Jag.