I'm picking parts for a friends PC, I think i'm decided on almost all of the parts although i am still open for suggestions on this if you want:
I5 2320 3Ghz
GeIL Value DDR3 4GB PC3 10660 1333Mhz
PowerColor HD 6870
my old NZXT M59 case
CCL choice 160GB 7200RPM
LiteOn iHOS104 4X Blu-Ra
Win 7 x64 HP
I'll be buying from either ebuyer.com or cclonline.com (i'm in the UK) and have a budget of £550
anyway, on to the main question: the bit that I am stuck on is the PSU, I am either looking at a OCZ ZS Series 550W (which looks like the safer choice atm) or an OCZ modxstream pro 500W.
in terms of wattage they both should be fine, but the modxstream is running 2 rails, which by the look of the OCZ documentation, should take 216W per rail, and on that rail, the graphics card, molex and sata connectors are being powered. so my question is, will the PSU be able to take the 6870 (probably overclocking in the future) along with an internal Blu ray drive and up to 3 HDDs on one 216W rail?
According to the various Techpowerup reviews 6870s on maximum load draw between 148-174W.
After startup modern HDD don't use more than 10W, so even taking the higher of those two figures you would be under the 216W.
So I don't think you would have any problems if you used the MXSP 500W.
But I think the ZS series 550W is the better choice, if only because of longer cables length and slightly more power overall on the 12V rails and being a newer, more efficient design. It also uses a dual ball bearing fan vs a sleeve on the MXSP 500W.