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New Rig - Help Determining PS Wattage

This is going to be my first custom rig, and I've been reading a lot to make sure I do this right. I've worked within my budget on most things and been able to find some discounts from friends to make it better than I hoped. A few of the final 'official' parts are still up in the air, but this is the basic breakdown.

Case - Thermaltake Element G
Processor - Intel Core i7 Extreme 965 (3.2GHz)
Hard Drives - Single SSD and Single Standard 500GB Drive
GPU - Dual ATI Radeon 5870 1GB Cards
RAM - 4x2GB Corsair Dominator

I'll also have assorted USB devices and a DVD drive, but nothing else of consequence. My friend recommended I use the Corsair CMPSU-1000HX that he got for his similar rig and said that he was recommended that by using several power supply calculators.

I used this one...
http://extreme.outervision.com/PSUEngine

I added everything in, and I'm only recommended 561W. I'd obviously want to go a bit higher than any recommendation just to be safe...but do I really need a PSU that is a 1000W?

With my setup, would I be able to go for a 750W or 850W?

Thanks in advance.
11 answers Last reply Best Answer
More about determining wattage
  1. You could safely go with a good quality 650W PSU.
    Your system is probably only using something like 350~400W 450-500W for 2.

    Have a really efficient PSU - maybe around 85%? That 500W measured at the wall socket means
    the system is actually drawing 425W DC power from the PSU.
  2. Doliath said:
    RAM - 4x2GB Corsair Dominator
    Not that it makes a big difference but it's 6GB, right?
  3. Here is an example:

    Processor(s): Intel Core i7 920 @ 3.8GHz (190MHz x 20)
    Cooling: Noctua NH-U12P (Supplied by Noctua)
    Motherboard(s): GIGABYTE EX58-UD5 (Supplied by GIGABYTE)
    Memory: 3 X 2GB OCZ Technology PC-12800 DDR-3 8-8-8-24 (OCZ3G1600LV6GK)
    Hard Disk(s): Western Digital 300GB Velicorapter (Supplied by Western Digital)
    TweakTown 5870 review
  4. Best answer
    Here are the official power requirements for the brand new ATI Radeon HD 5850 and HD 5870 video cards.


    ATI Radeon™ HD5850 System Requirements:

    PCI Express® based PC is required with one X16 lane graphics slot available on the motherboard

    500 Watt or greater power supply with two 75W 6-pin PCI Express® power connectors recommended
    600 Watt and four 6-pin connectors for ATI CrossFireX™ technology in dual mode


    ATI Radeon™ HD5870 System Requirements:

    PCI Express® based PC is required with one X16 lane graphics slot available on the motherboard
    500 Watt or greater power supply with two 75W 6-pin PCI Express® power connectors recommended
    600 Watt and four 6-pin connectors for ATI CrossFireX™ technology in • dual mode

    The power supply recommendations are for an entire pc system.

    Corsair, PC Power & Cooling, and Seasonic are some of the brands that have a reputation for high quality power supplies that consistently earn high marks in technical reviews. They are reliable, stable, and come with a 5 year warranty. Lately we've been seeing a few other brands offering some high quality units.
  5. You guys are great, that really cleared it up for me, thank you.
  6. How much $$ did we save you?
  7. W/ twin vid cards and OC'ing, my thinking is full tower case.....HAf 932 or Antec 1200

    For PSU, again, w/ OC'ing and twin cards, I'm thinking 850W Corsair HX or Antec Signature 850W.

    Here's a PSU calculator you don't have to d/l ....

    http://www.antec.outervision.com/

    for the drop downs, aside from all ya stuff (don't forget fans and connected USB / firewire stuff), I use:

    single socket
    85% TDP
    Hi end desktop
    90% CPU load
    25% capacitor aging

    and then multiple answer by 1.5 as PSU's efficiency drops as it gets above 70-80% load, voltages start to get wiggly, fans start to get noisy and why run something you wanna keep for a while at max rpm so to speak.

    Think 3 x 2GB on the RAM for the i7

    With 1 TB HD's going for $89, getting smaller doesn't really save much. Check THG charts for performance leaders (dont forget sound and temp charts)

    http://www.tomshardware.com/charts/2009-3.5-desktop-hard-drive-charts/benchmarks,50.html

    Note, 2 TB models have different performance than their 1 TB cousins and can't be compared.
  8. Dude, don't get the i7 965. If you want to go Extreme then get the 975 as it's a D0 stepping and is a smidge cooler, or save yourself a fortune get an i7 920 and clock the motherbitch up to match the Extremes.
  9. WR2 - You saved me a good amount, I appreciate it. :)

    JackNaylor - You are correct on the RAM, my mistake.

    LePhurronn - I chose the i7 965 because a friend of mine was able to provide a substantial discount because his wife works for Intel. It'd normally be quite a bit out of my budget, but with the discount it was hard to pass up. I'll check and see if he has the 975 as an option though.
  10. LePhuronn said:
    Dude, don't get the i7 965. If you want to go Extreme then get the 975 as it's a D0 stepping and is a smidge cooler, or save yourself a fortune get an i7 920 and clock the motherbitch up to match the Extremes.

    Nearly all the i7-920's in the pipeline now are D0 stepping. Look for the sSPEC of SELBJ on the box.
  11. Don't get a ps that meets the minimum or near minimum requirements. It'll starve your system for the power it needs and not run efficiently. The more strain you put on it it'll run hotter and wear out components quicker. For what you mentioned I'd look for something with 1 12v "rail" with 60-70 amps. You won't be sorry. Corsair...........

    don't look for watts, look for amps........... id rather have a ps with 60 amps on a 10 watt ps than a 1000 watt ps with 10 amps......
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