My friend's trying to sell me his computer...

buying used and saying you are buying someone else problem is not very good logic after all GM sold million of cars with a busted ignition so tell me how buying new promises you something better or safer? the product is only as good as it is made

buying used has it risk but in most cases it is a good bet i have had new stuff fail on me and yet my almost 15 year stereo receiver is still going strong and so is my used xbox slim,a long with my free a/c and so on

the only thing i would be cautious on buying used for the pc is the video card as the cpu tend to out last the hardware everything and the 2500k is still a very strong pc i know here in the U.S that cpu and motherboard still sell for around 200 the cpu itself usually sells for around 150

price the parts where you are from and decide from there it is a really good starting gaming pc later you could always upgrade the gpu if you find you need more

and ask yourself how trustful this person is and if he really knows computers and ask why he is selling it,and ask if he will offer some kind of warranty if it is family or really close friend and i sell them something used i will offer them at least some tech help and 30 days

but in the end only you can decide what to do but price wise here in the U.S. all that is a bit high priced but you could offer a lower price if he really needs money he will go lower

good luck

See the cost breakdown below. It's hard to name an accurate price without knowing every part of the pc. But performance-wise, it's more like 300 - 350. Depending on where you live you can build a new, faster pc with 450 - 500 bucks, so I'd rather do that instead of paying 400 for a used machine.

Because it's 317.75 plus taxes.

I search for the lowest price online for every piece and remove 22% of the price (because 22% is our current VAT here) which makes the actual value of a NEW piece, then i cut another 10% to 50% depending on the conditions of the computer, aging and such (missing boxes, no warranty, overclocked GPU/CPU, faulty memories, format...).

Case and PSU are considered as cheap stock pieces since there's no information about them. If the PSU is good enough i might add another 25-30 €.

its his friend ...low ball his friend ?

Cheapest Prices in some EU Countries (website in german)
Price at Amazon
Don't find the i5-2550k for the 150€ you are talking about.
Sure you don't mean the 2500k?

Also the i5-4670k is not less than 200€ but the i5-4670 is.

Sandy Bridge CPUs stay cooler and are better for overclocking than Ivy Bridge and Haswell CPUs because of this. I had my i5-2500K @ 4.4GHz and the temperature was always under 70°C. i5-4670K at the same clock speed would run at a much higher temperature.

Problem is its NOT a top of the line model, its your average $700-800~ build 2 years ago.
The GTX 660 even at it's prime was a budget card and at the moment it easily gets outclassed by a $115(85€) R9 270. More importantly it's USED you can get used GTX 660s for as low at $100(70€) on Kijiji or Craiglist or whatever you have in Finland.

The i5-2550k at it's prime was a GREAT card, however its slowly getting dated and realistically no one would buy this anymore. You can get a much better i5 4590k for the price this thing is going for, the prices people are posting are prices that haven't been updated at all. I'd say a used i5 2550k is worth $120(90€) at best.

Case - We're talking about you buying a case at retail price that you might even like, jesus christ. $25 (18€ )

Motherboard - I don't know where people found out what your motherboard specs are but ones for i5 2550k can easily be bought for $70-80(50€) NEW not USED, so I would give this a price adjustment of $50(40€).

CPU Cooler - Thermalright makes some entry level/crap level to mid level cpu coolers. The cheapest ones they make are $26(20€)

RAM - 8 GB of ram should cost $80 USD (60€) I HAVE NO IDEA WHO PAYS $100(80€) for 1600mhz ram. You know who I'm pointing at.

HDD: 56€? That better be a 1.5TB HDD you can generally get a 1TB fresh Seagate/WD (Good Brand Names) for 40€ or $50

PSU: Once again not enough clear information, you are either forgetting something or your friend is telling you something. If you can get some pictures of the inner components. PSUs can range from dirt cheap no brand to high end 80+ Platinums. Basically anywhere from $20(15€) to $140(100€)

TLDR: Not enough information, to many people here aren't properly adjusting price to date and including the fact its used. However, final verdict is, meh should be a pretty good deal. I'd say the real adjusted cost as of today for this used build would be around 400€ to 475€. I would try to grab it for less then 400€ though.

Forgot to mention, to ACTUALLY make good use of this build you would most likely need a clear UNDERSTANDING of how to OVERCLOCK. Otherwise you have a useless CPU Cooler and a useless unlocked CPU, which is basically $60+ (40€) OF DEAD WEIGHT.

Thanks for the tip! Will surely do that.

Most of it is actually pretty easy to check using the HDD SMART data.