If you are considering the hiper have a look at the Sunbeam NUUO 550w it is not as nice looking but they have a $20 instant rebate so it is much easier on the wallet ($55/$64 shipped!). Same 30A output on the +12v, read a detailed review here.
or can someone suggest another (better) psu in the price range of those above. it is important that its modular.
I personally own the Hiper and am very happy with it. It is clean and quiet which is exactly what i was looking for. The connectors are very easy to connect and i like the fact that they screw in so you don't need to worry about them coming loose as with past PSU's of this type.
And also check out: http://www.jonnyguru.com/ It has some great reviews and it taught me a lot about PSU's and what to look for etc.
In my honest opinion, as you are in Europe (like me), some Class 1 brands like PCP&C and Zippy are not available to buy for us. You can only find them in the States.
Look out for Silverstone ZF series, Corsair HX, OCZ GameXstream.
I am going to buy the Corsair HX 620W as it has rave reviews, 5 year warranty, rock solid rails, very efficient, has 50A on the 12V rail and is in fact a single rail, not triple as stated. Check Jonny Gurus review here:
I own the 600W Xclio Greatpower and I like it a lot. Its more efficient than the Hiper as well. The 14cm fan is very large, but it whisper quite. My new setup as in my sig is so much quiter than my old p4 Northwood, generic power supply, and a 5900XT.
Be warned with the Xclio instructions, took my 45 minutes to figure out that their 'server connector' splits in two to give you 2 P4 4 pin connectors. I thought I bought a PS w/o a P4 4pin connector and generated a large headache.
The Xclio out of those two, definite, it's a shame you're not in the UK, as the GREATPOWER series are incredible value over here, they are well built, stable, quiet, quality PSU's and offer great bang for the buck.
Over on OCUK there's seems to have been a lot of bother with Hiper recently, i'm not sure which model, it's probably just a bad batch.
Others have mentioned OCZ gamestream, and the Corsair 520W and 620W, and you can't go wrong with either.
Between the two, I'd go with the hiper. It's not 700 watts, but the rails are very stable on the hiper. Although, I do agree with doolittle. The sunbeam nuuo is a very good psu for the price. I know this because I have used it before and test the rails. It never went out of spec. I love mod cabling and always look for it now when purchasing a new psu.
Well if you were reading my "Hiper Opinion" thread I just got talked off from getting the Hiper Type-R. Instead I'm going for the Zalman ZM600. I would have gone for the Corsair 620HX but it was just a tad more expensive and out of stock at the retailer I was using.