Help Choosing Power Supply

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uwstonedprophet

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Feb 9, 2009
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Hi there. I'm building a computer, but haven't done this in a while. Just want to make sure none of these individual parts stand out as either overkill or as not powerful enough (relative to the rest of the system). Also, I have tried to calculate the wattage needed for this system, but am not sure I'm doing it right. In the future I intend to add another Radeon 4870 to run in crossfire, so I need to leave headroom in the wattage for the power supply. Can anyone show me how to calculate this? And one last question, what's a good case that will fit all these components? Thx ahead of time for any help. :) The specs are listed below.


Intel Q9550 w/ Xigmatek HDT-S1283 Heatsink/Cooling Fan and Xigmatek Crossbow
Gigabyte GA-EP45-UD3P Mobo
Sapphire Radeon HD4870 1GB
G. Skill 4x2GB 800MHz PC2-6400 DDR2 DIMM
Samsung Spinpoint F1 1TB HD
Lite-On DH-401S-11 Black Blu-ray Reader
Linksys WMP54G Wireless Network Adapter
 
You'll need a 750W PSU, the red PCP&C Silencer 750 is on sale at Newegg for $80 after MIR. The other candidate is the Corsair 750TX.

Use these as guides to PSU requirements:

Power Supply Calculator

Power Requirements Article

I would go with the WD Caviar Black 1TB if you only have one HDD.

For Blu-ray readers, I like the LG GGC-H20L.

Coolermaster CM-690 is nice, as well as Antec 900, NZXT Tempest, and Thermaltake Armor series. Try these for a start, but go with one that you like.

Don't forget MX-2 thermal paste.
 
Actually, without cpu paste your cooler in not worthless. After listening to the advice of posters here, I did my undermost best to put as little cpu paste on as possible. Thinking that their was some paste on, and I couldn't see it, I happily put the cooler in, and when I checked my cpu temperature after all the software installs, the temp seemed a bit high. Long story short, I reapplied the paste, and learned from my silly mistake. But, yes, a cpu cooler will work without paste and keep your cpu safe, just not efficiently or under load 😱 .
 
Re: Thermal Paste

To be a little more precise, the thermal paste fills in the microscopic valleys on the two contact surfaces, enhancing the thermal conductivity between CPU heatspreader and heatsink base. Hence, less is more. If there were some way to make the surfaces without microscopic pits and have perfect metal to metal contact, then thermal paste would not be necessary. Just remember that it doesn't work like glue... 😉
 
Hey guys before I make this purchase, thanks again for your help. Think I'm probably goin to go with the corsair 750TX PSU and the NZXT tempest case. :) Just gotta make sure the corsair has a long enough cord to the mobo, cuz I guess that can be an issue with the NZXT.

I am also wondering, as per an earlier post: why the WD Caviar Black 1TB over the Samsung Spinpoint F1 1TB? Seems most every chart on Tom's shows the Samsung as faster except for random access time. Thanks again!
 
It's true, the Spinpoint F1 1TB is one of the fastest disks out there. I remember seeing some benchmarks like 120 MB/s average read. The WD is around 100 MB/s. The problem with the Spinpoint is that it was less reliable than normal.

Look at Newegg reviews:

The Spinpoint: 14% give it one egg. Usually that means the disk failed. The WD is hated by only 5% of reviewers.
http://www.newegg.com/Product/Product.aspx?Item=N82E16822152102
http://www.newegg.com/Product/Product.aspx?Item=N82E16822136284
 
OK thanks! I'll go with the WD for reliability then I think. Can someone confirm that the Corsair 750 TX will be enough with two 4870s running in xfire? I put everything into the power calculator above and it came out closer to 850W.. this is a bit confusing to me.
 


Let me guess, you selected Quad Socket, because Q9550 has 4 cores, didn't you? Everybody does that, it's a misleading GUI.
However, quad socket means 4 Q9550 CPUs for a total of 16 cores, and it ruined your calculations :)
 
Oh also... lol seems like there's always one more thing. Just want to make sure I do this right the first time! I'm looking now at the 4x2GB of the G. Skill PI Black (900MHz). Does the 900 MHz mean it's overclocked from 800 MHz? Also.. I understand there is a 2x multiplier on the ram so it's actually running at 450 MHz. My Q9550 has a multiplier of 4x on the fsb at 1333 MHz, which means it is actually running at 333 MHz. Can I overclock the processor up to 450 MHz so that the processor and memory are running in sync? Or will that burn it up? Want to have this machine running all syncd up but really don't want to fry anything.
 
If you're worried about the reach of the 8-pin mobo connector, then get an extension cord like this: link.

Regarding the Spinpoint vs. Caviar Black, if you read the Tom's Hardware review, there is also a chart that shows the profile of the drive's operating characteristics. The Caviar Black works better as a system drive (doing various different tasks) while the Spinpoint just blasts the data through at a higher rate, but is not quite as good at the multitasking test. Hence, it works better as a data drive. If you only have one drive, then it must do everything--hence I suggested the Caviar Black.

I'm also with aevm, in that reliability is quite an important factor for HDDs since they store the most important thing of all on your PC.

Overclocked Q9550 + 4870 Crossfire = Corsair 750TX or PCP&C Silencer 750.

With the Corsair 750TX, you'll have to mount it "upside-down" with the big fan facing up into the case, for best airflow. I, like aevm, also prefer the straight-through airflow design of PCP&C.

If you use 1:1 synchronous mode, your memory will wind up running DDR2-900 max. Doubt you will be able to OC your Q9550 beyond 450FSB, which means DDR2-900. The Pi Black 900s are guaranteed to run at that speed, with 2.0-2.1V. If you buy the 800 version, it's specified to run at 1.8-1.9V. So when you go to OC, then you will also have to up the voltage on the 800s to get above 800 speed, most likely. They are really the same RAM, just that one is "factory OC'd" and specified to run at 900.

The other way to look at it is that if you buy the 800s, then you will have to up the voltage and perhaps loosen timings to get to your OC speed. If you buy the 900s, then you can reduce voltage to run stable at your OC speed. It's just coming to the same point from two different directions. They are the same price, so it doesn't really matter, but I'd be inclined to get the 900s because the factory is guaranteeing a better speed (these are also the RAM modules from the "higher quality bin"). Heck, you could always set your BIOS with the 800's specs if you wanted. G.Skill is basically telling you that the 100MHz gap can be bridged solely with additional voltage.

If you want to run asynchronous memory dividers, then you're on your own and no guarantees. Try up to 2.1V with 5-5-5-18 or tighter timings.
 
Can I just thank you again? Thx Ake n aevm, I really appreciate your help. PI Black it is then. You might hear from me again once I get the parts. I'm sure I'll have plenty of questions then too. :)
 
I've heard the corsair is quieter btw running under full load.. which is why I was leaning towards it. Have you heard whether it's a pain to mount it "upside-down." I don't mind what it looks like so much inside so long as it's tidy for air flow and runs well.
 
OK, I did a bit of research. It's true, the 750TX is quieter at 80% or more.


750TX: 40 dBA under load of 550W or more, at 25 Celisus, 1 meter away.
http://www.anandtech.com/casecoolingpsus/showdoc.aspx?i=3445&p=8

Silencer 750W: 44dBA, same conditions.
http://www.anandtech.com/casecoolingpsus/showdoc.aspx?i=3040&p=16


Mind you, you shouldn't buy a 750W PSU if you expect to use it at 80% or more. You should get a Corsair 850TX or 1000HX or similar for that sort of thing. Efficiency drops after 80%, which means more heat, lower part lifetime, higher electricity bills, and added noise, sure.
 
I have a Silencer S75CF 750W (the red one). The only noise it makes is a funny beep at shutdown. But, on the other hand, I've never made it deliver 500W or more. I've got a Q6600, an 8800GTX and 5 hard drives.
 
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