SHE'S a soft porn star. A singer. A chat show hostess. A ''serious'' movie actress. A model. But the scorching pace of a showbiz career that now spans almost every mode of media entertainment has finally caught up with Ronnie Yip Yuk-hing. Two weeks ago, the 27-year-old multi-millionairess collapsed on a New Territories film set and was taken to hospital suffering from exhaustion. But such is the allure of the limelight, two days later she was back at work, slogging through interviews, recording work, photo sessions and filming her 20th movie in two years. In short, being Hongkong's most in-demand celebrity. Yip should have plenty to be happy about, but the dazzling smile faded one day last week as she admitted she had worked herself to a standstill, and also to the brink of serious health problems. ''My physical condition is not good,'' admitted the woman who three years ago was a struggling, modestly-paid contract artiste at Asia Television Ltd. ''I usually only sleep three to four hours a day. I have been very tired and overloaded with work. When I collapsed I had an infection . . . like a really bad cold, which was quite hard to recover from because I was so tired. ''I went to the hospital to have a check and the report came out that everything was OK. They just told me to slow my work down and sleep at least eight hours a day.'' What she neglected to mention was the fact that she has lost nine kilograms in the past year and that her friends and family have said they are worried about her. So, too, is the entertainment press - which in its own compassionate way has dwelt at length on the Yip diet and even diagnosed anorexia. Yip's concession to the fuss was to announce a six-month break from filming. But that still leaves her with her weekly TVB Jade chat show, Tonight With Veronica, promotional activities for her latest album, a concert tour of China this summer, photo spreads for countless magazines, press interviews and private business dealings, which are said to include a new hair salon. But the spectre of burn-out is looming over Yip. As if aware of it, she spent 45 minutes last week insisting with a conviction bordering on the suspicious that she is perfectly all right. Honest. There is no doubt the summer 1993 model Yip is a far more economical one than that which bounced on to Hongkong's movie screens in 1991 with a series of nude appearances in films like Hidden Desires, Pretty Woman and Take Me. The trademark low-cut dress is still there, flashing cleavage aplenty, but the once curvaceous star is almost Hepburn-slim about the upper arms and neckline. Her face is more angular, the cheekbones prominent and the entire drawn effect heightened by a new-look slash of vermilion across her lips. ''I prefer to look the way I do now, really,'' insisted Yip over cigarettes and coffee at a Kowloon hotel. ''I feel it looks more fit. I simply lost weight because of the stress and the pressure. ''I do worry about being fat because the cameras make you look fat. I feel pressure now because people say I am too thin, but I think I look OK.'' Her widely-publicised break from film-making, she said with similar conviction, was aimed at allowing her to pick and choose quality roles in future. So much for the rumours. But it wasn't long before she let down the guard. ''You know why I went straight from the hospital back to work? It's because I like to work hard. Once you become popular, it's usually not forever so you have to take the chance while you've got it,'' she said. ''You have to do the work when it's there. I think people are so busy now because they want to make a lot of money before 1997. And that's the way artists are in Hongkong's entertainment circle. ''You may be dropped one day and you won't know it's coming. People will forget you if they don't see you regularly.'' Hence the Yip regime. She is not the only actress in Hongkong to have become swept up in an exhausting programme involving shooting several films at the same time, but Yip's ambition sets her aside. Those 20 films in two years have been made at a staggering rate, but they have also seen Yip develop from category III pin-up into a respected actress, whose most recent films include the lyrical Lawrence Ah Mon production, Three Summers. With her albums, she spent 10 days in the studio (''a song a day'', she proudly reveals) and she lamented the depressed state of the entertainment industry in countries like Taiwan which ruled out the possibility of a massive Southeast Asian concert slog after her China dates in August and September. There must be more to the woman's burning ambition than a classic Hongkong get-on-with-it mentality. And she admitted it may lie in her past. ''I think I deserve the success,'' she declared. ''I was waiting for six or seven years in television before it happened so, yes, I deserve it.'' Then there is the manner of her lucky break. Yip literally burst on to the entertainment scene over night. Back in the wild days of 1991 when businessmen were on trial for procuring sex acts from starlets, and category III was sweating and panting its way into our consciousness, Yip took a weighty decision. She appeared naked but for a necklace on the cover of a mass circulation Chinese magazine, was sacked by ATV for her pains and then plunged headlong into the soft porn business. It was a far cry from the day in 1985 when the girl from a well-to-do Hongkong family finished runner-up in the Miss Asia Pacific beauty contest and thought fame and fortune awaited. But at least she had arrived. And, unlike her namesake and partner in prurience, Amy, Yip won over the critics and now counts as a bona fide player on the Hongkong scene. ''At times the media has been tough with me and criticised me a lot,'' she admitted. ''Not so much now but at the beginning it was quite bad. But the reporters, most of them are very kind to me now. ''There have been a lot of films I was involved in that weren't good quality. ''Good quality is very important but money is important, too, and when I become comfortable with the money I have made then I can afford to choose the films I will make. ''When I return to films I will only be making one or two a year. I only want to take part in good quality ones. ''I always work hard for the role I take part in. I have always done my best. But when the films come out, because of the low budget, the bad quality of equipment and people, the results are not always so good. It's not fair.'' But even after she begins her new, more selective, role as a quality actress, Yip has no burning desire to drop the rest of her commitments. ''I might slow down in two years,'' she murmured, with a side-long glance at her assistant. ''I want to buy a house with my money and I hope soon I can spend more time with friends. I want to live with my mum and spend the rest of her years with her because she's getting old and I want to take care of her.'' But she becomes far more animated about her plans outside the entertainment industry. ''I want to do business,'' she insisted, before launching into a well-thought-out scheme aimed at selling her own brand of clothing, designed in Europe and manufactured locally, to the massive market in mainland China. But enough dreaming. Having picked half-heartedly at a bread roll or two, Yip adjusted the make up and headed off once more in search of success and those all-important dollars. It's a shame she cut such a skinny figure as she did so. Two days in the life of Ronnie 7.30am - 8am: Wakes up. 8am - 10am: Showers, puts on make-up, dresses and prepares clothes for the day's appointments. Heads from her Kowloon flat to Clear Water Bay for her first job of the day. 10am - 11am: Works on material for her TVB Jade talk show. Noon: Three-hour photo session in studio with Ming Pao Daily News. 3pm - 6pm: Three-hour photo session with an entertainment magazine. 6pm - 6am: Overnight film shooting on an as-yet-untitled costume drama in various locations. Then home. NEXT DAY 1pm: Wakes up, showers, prepares make-up and clothes. 3pm: Photo session with Next Magazine. 8pm: Records chat show at TV City. Midnight - 6am: Overnight film shooting.