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Which replacement PSU for an older PC?

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December 8, 2013 12:45:48 PM

I have just acquired a 2009-ish era custom PC, based on a Q6600 CPU, speccs as follows:
Intel Core 2 Quad Q6600 G0
Arctic Cooling AC-FRZ-7P Freezer 7 Pro CPU cooler
Gigabyte GA-EP45-DS3R P45 Mobo
EVGA 9800GTX+ SC 512MB (DDR3)
Kingston 4x2GB DDR2 800MHz/PC2-6400 HyperX Memory
Maxtor 500GB HDD 7200rpm, 32MB cache
Cti 700ub PSU
Coolermaster Elite 330 case

I want to mildly overclock the Q6600 (to around 3 GHz) and add several more HDDs. The primary use of the PC is everyday/office with occasional photo-editing, digital map manipulation and some (simple) 3D CAD work.

Sadly the existing PSU, a Cti 700UB, is sub-par for this. Although nominally 700W, there is only 21A on each of 2 12V rails, and no mention of the total Amps. No positive reviews exist…..

So an upgrade seems in order, but this is an old PC and I am on a tight budget. I have 2 related questions really:

1) Is a 450-500W PSU likely to be sufficient?
Using the manual method outlined on this site, I calculated a max load of about 360W on the above system (with OC’d Q6600), which would require a total of 30A on the 12V rails. The eXtreme calculator came up with 410 W as the minimum. The EVGA 9800 recommendations are for a minimum of 450W PSU, with minimum of 26A on the 12V rail. Since I don’t do plan to do any other significant upgrades, I thought a 450-500W PSU should give enough headroom. I hope that there are people here who can advise.

2) Assuming 1) above is right, then which PSU?
I don’t really want to spend more than £40. I found 2 which might do, as follows;

A - Silverstone SST-ST50F-ES-230 Strider Essential 500W, £35 at http://www.scan.co.uk/products/500w-silverstone-strider...
This PSU has been reviewed on this site (http://www.tomshardware.com/reviews/500w-psu-power-supp...). It was well received, and only failed to get 80PLUS certification because it is designed for 230 V operation only (so can’t be used in the US – not a problem for me). Energy efficiency exceeds 80% above an 85W load, but is poor below that. I don’t think this is a problem for me – I estimate that the q6600 and 9800GTX+ combined will be around 100W at idle.

B - XFX P1-450S-X2B9 Pro, £34 at http://www.scan.co.uk/products/450w-xfx-pro-core-editio.... I believe from reading that this is a re-badged Seasonic S12II, which has been highly rated in many reviews.

I would appreciate any advice regarding whether my power calculations are right, if the PSUs are a good choice, or if there are any other alternatives that I have missed.

More about : replacement psu older

December 8, 2013 1:35:48 PM

1. The power requirements are almost entirely determined by the graphics card.
Hard drives and such add very little load.
A 9800GTX with normal peripherals would run nicely on a 450W psu.
The 26a refers to the total capability of the psu on all the +12v rail(S). That is rarely the sum of the rails, but a 700w psu should be OK.

May I suggest instead that you buy a 120gb SSD for the os and some apps. It will make even an older pc feel like new in everyday work.
Unless your psu is of poor quality or failing I would continue to use it.




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